RCC Exported Functions

Modules
	HSE
	HSI
	CSI
	HSI48
	D1CKREADY
	D2CKREADY
	RESET
	LSE
	LSI
	System
	MCO
	Peripheral Clock Source
	RTC
	TIM
	PLL
	FLAG Management
	IT Management
	De-initialization function
	Get system and peripherals clocks frequency functions
	Return the frequencies of different on chip clocks; System, AHB, APB1, APB2, APB3 and APB4 buses clocks.