fix ci build

- nuc 121/125: add CFG_EXAMPLE_MSC_READONLY since it is not enough SRAM
to hold MSC disk
- nuc 126: drop i2c source files in compile list due to SDK driver
issue.

hw/bsp/nutiny_nuc121s/board.mk

@@ -5,6 +5,7 @@ CFLAGS += \
   -mcpu=cortex-m0 \
   -D__ARM_FEATURE_DSP=0 \
   -DUSE_ASSERT=0 \
+  -DCFG_EXAMPLE_MSC_READONLY \
   -DCFG_TUSB_MCU=OPT_MCU_NUC121
 
 # All source paths should be relative to the top level.

hw/bsp/nutiny_nuc125s/board.mk

@@ -5,6 +5,7 @@ CFLAGS += \
   -mcpu=cortex-m0 \
   -D__ARM_FEATURE_DSP=0 \
   -DUSE_ASSERT=0 \
+  -DCFG_EXAMPLE_MSC_READONLY \
   -DCFG_TUSB_MCU=OPT_MCU_NUC121
 
 # All source paths should be relative to the top level.

hw/bsp/nutiny_nuc126v/board.mk

@@ -20,7 +20,6 @@ SRC_C += \
   hw/mcu/nuvoton/nuc126/StdDriver/src/ebi.c \
   hw/mcu/nuvoton/nuc126/StdDriver/src/fmc.c \
   hw/mcu/nuvoton/nuc126/StdDriver/src/gpio.c \
-  hw/mcu/nuvoton/nuc126/StdDriver/src/i2c.c \
   hw/mcu/nuvoton/nuc126/StdDriver/src/pdma.c \
   hw/mcu/nuvoton/nuc126/StdDriver/src/pwm.c \
   hw/mcu/nuvoton/nuc126/StdDriver/src/rtc.c \
@@ -32,7 +31,6 @@ SRC_C += \
   hw/mcu/nuvoton/nuc126/StdDriver/src/timer_pwm.c \
   hw/mcu/nuvoton/nuc126/StdDriver/src/uart.c \
   hw/mcu/nuvoton/nuc126/StdDriver/src/usbd.c \
-  hw/mcu/nuvoton/nuc126/StdDriver/src/usci_i2c.c \
   hw/mcu/nuvoton/nuc126/StdDriver/src/usci_spi.c \
   hw/mcu/nuvoton/nuc126/StdDriver/src/usci_uart.c \
   hw/mcu/nuvoton/nuc126/StdDriver/src/wdt.c \