Inline, fewer LOC, remove redundant definition in cpp.

Author: dok-net

cores/esp8266/Esp.cpp

@@ -264,13 +264,6 @@ uint8_t EspClass::getBootMode(void)
     return system_get_boot_mode();
 }
 
-#ifndef F_CPU
-uint8_t EspClass::getCpuFreqMHz(void)
-{
-    return system_get_cpu_freq();
-}
-#endif
-
 uint32_t EspClass::getFlashChipId(void)
 {
     static uint32_t flash_chip_id = 0;

cores/esp8266/Esp.h

@@ -123,12 +123,12 @@ class EspClass {
 
 #if defined(F_CPU) || defined(CORE_MOCK)
         constexpr uint8_t getCpuFreqMHz() const
+#else
+        uint8_t getCpuFreqMHz() const
+#endif
         {
             return esp_get_cpu_freq_mhz();
         }
-#else
-        uint8_t getCpuFreqMHz() const;
-#endif
 
         uint32_t getFlashChipId();
         uint8_t getFlashChipVendorId();