fix(esp8266): remove 40MHz STAL option

components/esp8266/Kconfig

@@ -254,19 +254,6 @@ config ESP8266_CORE_GLOBAL_DATA_LINK_IRAM
     help
         Link libcore.a internal global data(.bss .data COMMON) from DRAM to IRAM.
 
-choice CRYSTAL_USED
-    prompt "Crystal used in your module or board"
-    default CRYSTAL_USED_26MHZ
-    help
-        For most modules, 26MHz is the default crystal. If you use special module,
-        you can reconfigure this option.
-
-config CRYSTAL_USED_26MHZ
-    bool "26MHz"
-config CRYSTAL_USED_40MHZ
-    bool "40MHz"
-endchoice
-
 config INIT_OS_BEFORE_START
     bool "Init OS before starting it"
     default n

components/esp8266/include/esp_system.h

@@ -27,13 +27,7 @@
 extern "C" {
 #endif
 
-#if CONFIG_CRYSTAL_USED_26MHZ
 #define CRYSTAL_USED 26
-#endif
-
-#if CONFIG_CRYSTAL_USED_40MHZ
-#define CRYSTAL_USED 40
-#endif
 
 typedef enum {
     ESP_MAC_WIFI_STA,