SystemClockHSI_Config() function

Switch the PLL source from HSI to HSE, and select the PLL as SYSCLK source. The system Clock is configured as follow : System Clock source = PLL (HSI) SYSCLK(Hz) = 168000000 HCLK(Hz) = 168000000 AHB Prescaler = 1 APB1 Prescaler = 4 APB2 Prescaler = 2 HSI Frequency(Hz) = 16000000 PLL_M = 16 PLL_N = 336 PLL_P = 2 VDD(V) = 3.3 Main regulator output voltage = Scale1 mode Flash Latency(WS) = 5