fix(esp8266): esp8266 flash mapping to CPU bus size only supports 1MB now
We may add support to run app which size is larger than 1MB later.
#define IRAM_SIZE (48 * 1024)
#define FLASH_BASE (0x40200000)
-#define FLASH_SIZE (2 * 1024 * 1024)
+#define FLASH_SIZE (1 * 1024 * 1024)
#define RTC_SYS_BASE (0x60001000)
#define RTC_SYS_SIZE (0x200)
