soc: add dummy bytes to ensure instr prefetch always valid

The CPU might prefetch instructions, which means it in some cases
will try to fetch instruction located after the last instruction in
flash.text.

Add dummy bytes to ensure fetching these wont result in an error,
 e.g. MMU exceptions

components/bootloader/subproject/main/ld/esp32/bootloader.ld

@@ -165,6 +165,14 @@ SECTIONS
     *(.fini.literal)
     *(.fini)
     *(.gnu.version)
+
+    /** CPU will try to prefetch up to 16 bytes of
+      * of instructions. This means that any configuration (e.g. MMU, PMS) must allow
+      * safe access to up to 16 bytes after the last real instruction, add
+      * dummy bytes to ensure this
+      */
+    . += 16;
+
     _text_end = ABSOLUTE(.);
     _etext = .;
   } > iram_seg

components/bootloader/subproject/main/ld/esp32s2beta/bootloader.ld

@@ -157,6 +157,14 @@ SECTIONS
     *(.fini.literal)
     *(.fini)
     *(.gnu.version)
+
+    /** CPU will try to prefetch up to 16 bytes of
+      * of instructions. This means that any configuration (e.g. MMU, PMS) must allow
+      * safe access to up to 16 bytes after the last real instruction, add
+      * dummy bytes to ensure this
+      */
+    . += 16;
+
     _text_end = ABSOLUTE(.);
     _etext = .;
   } > iram_seg

components/esp32/ld/esp32.project.ld.in

@@ -324,6 +324,14 @@ SECTIONS
     *(.fini.literal)
     *(.fini)
     *(.gnu.version)
+
+    /** CPU will try to prefetch up to 16 bytes of
+      * of instructions. This means that any configuration (e.g. MMU, PMS) must allow
+      * safe access to up to 16 bytes after the last real instruction, add
+      * dummy bytes to ensure this
+      */
+    . += 16;
+
     _text_end = ABSOLUTE(.);
     _etext = .;
 

components/esp32s2beta/ld/esp32s2beta.project.ld.in

@@ -321,6 +321,14 @@ SECTIONS
     *(.fini.literal)
     *(.fini)
     *(.gnu.version)
+
+    /** CPU will try to prefetch up to 16 bytes of
+      * of instructions. This means that any configuration (e.g. MMU, PMS) must allow
+      * safe access to up to 16 bytes after the last real instruction, add
+      * dummy bytes to ensure this
+      */
+    . += 16;
+
     _text_end = ABSOLUTE(.);
     _etext = .;