examples: Add the fast wakeup option for deep sleep examples

The CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP option is enabled
by default for the following examples:
 - system/deep_sleep,
 - system/ulp,
 - system/ulp_adc.

examples/system/deep_sleep/README.md

@@ -9,3 +9,4 @@ The following wake up sources are configured:
 - Touch: wake up the chip if any of the touch pads are pressed (GPIO32, GPIO33)
 - ULP: wake up when the chip temperature changes by more than ~5 degrees Celsius (this value hasn't been characterized exactly yet).
 
+In this example, the `CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP` Kconfig option is used, which allows you to reduce the boot time of the bootloader during waking up from deep sleep. The bootloader stores in rtc memory the address of a running partition and uses it when it wakes up. This example allows you to skip all image checks and speed up the boot.

examples/system/deep_sleep/sdkconfig.defaults

@@ -4,3 +4,4 @@ CONFIG_ESP32_ULP_COPROC_ENABLED=y
 CONFIG_ESP32_ULP_COPROC_RESERVE_MEM=512
 CONFIG_ESP32_TIME_SYSCALL_USE_RTC_FRC1=y
 CONFIG_ESP32_RTC_CLK_SRC_INT_RC=y
+CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP=y

examples/system/ulp/README.md

@@ -12,6 +12,8 @@ Upon wakeup, the main program saves total edge count into NVS and returns to dee
 
 In this example the input signal is connected to GPIO0. Note that this pin was chosen because most development boards have a button connected to it, so the pulses to be counted can be generated by pressing the button. For real world applications this is not a good choice of a pin, because GPIO0 also acts as a bootstrapping pin. To change the pin number, check the ESP32 Chip Pin List document and adjust `gpio_num` and `ulp_io_number` variables in main.c.
 
+In this example, the `CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP` Kconfig option is used, which allows you to reduce the boot time of the bootloader during waking up from deep sleep. The bootloader stores in rtc memory the address of a running partition and uses it when it wakes up. This example allows you to skip all image checks and speed up the boot.
+
 ## Example output
 
 ```

examples/system/ulp/sdkconfig.defaults

@@ -6,3 +6,4 @@ CONFIG_BOOTLOADER_LOG_LEVEL_WARN=y
 CONFIG_BOOTLOADER_LOG_LEVEL=2
 CONFIG_LOG_DEFAULT_LEVEL_WARN=y
 CONFIG_LOG_DEFAULT_LEVEL=2
+CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP=y

examples/system/ulp_adc/README.md

@@ -16,6 +16,8 @@ Measurement frequency, Hz | Average current, uA
   50                      | 20
  100                      | 37
 
+In this example, the `CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP` Kconfig option is used, which allows you to reduce the boot time of the bootloader during waking up from deep sleep. The bootloader stores in rtc memory the address of a running partition and uses it when it wakes up. This example allows you to skip all image checks and speed up the boot.
+
 ## Example output
 
 Below is the output from this example.

examples/system/ulp_adc/sdkconfig.defaults

@@ -6,3 +6,4 @@ CONFIG_BOOTLOADER_LOG_LEVEL_WARN=y
 CONFIG_BOOTLOADER_LOG_LEVEL=2
 CONFIG_LOG_DEFAULT_LEVEL_WARN=y
 CONFIG_LOG_DEFAULT_LEVEL=2
+CONFIG_BOOTLOADER_SKIP_VALIDATE_IN_DEEP_SLEEP=y