esp8266: Put mp_keyboard_interrupt in IRAM.

It was originally in IRAM due to the linker script specification, but
since the function moved from lib/utils/interrupt_char.c to py/scheduler.c
it needs to be put back in IRAM.

ports/esp8266/boards/esp8266_common.ld

@@ -140,7 +140,7 @@ SECTIONS
         *lib/utils/sys_stdio_mphal.o*(.literal*, .text*)
         *lib/utils/pyexec.o*(.literal*, .text*)
         *lib/utils/stdout_helpers.o*(.literal*, .text*)
-        *lib/utils/interrupt_char.o*(.literal.mp_hal_set_interrupt_char, .text.mp_hal_set_interrupt_char)
+        *lib/utils/interrupt_char.o*(.literal*, .text*)
         *drivers/bus/*.o(.literal* .text*)
 
         build-*/main.o(.literal* .text*)

ports/esp8266/mpconfigport.h

@@ -191,5 +191,6 @@ extern const struct _mp_obj_module_t mp_module_onewire;
 #define MICROPY_PY_SYS_PLATFORM "esp8266"
 
 #define MP_FASTCODE(n) __attribute__((section(".iram0.text." #n))) n
+#define MICROPY_WRAP_MP_KEYBOARD_INTERRUPT(f) MP_FASTCODE(f)
 
 #define _assert(expr) ((expr) ? (void)0 : __assert_func(__FILE__, __LINE__, __func__, #expr))