ESP.getCpuFreqMHz fix (#3007)

* ESP.getCpuFreqMHz was returning the CONFIG_ variable. Now calls the getCpuFrequencyMhz function. * Changed the Esp function to uint32_t to match

Author: lbernstone

cores/esp32/Esp.h

@@ -75,7 +75,7 @@ class EspClass
 uint32_tgetMaxAllocPsram();
 
 uint8_tgetChipRevision();
-uint8_tgetCpuFreqMHz(){ returnCONFIG_ESP32_DEFAULT_CPU_FREQ_MHZ; }
+uint32_tgetCpuFreqMHz(){ returngetCpuFrequencyMhz(); }
 uint32_tgetCycleCount();
 constchar * getSdkVersion();