rtc: bindings: Supply knowledge of a third supported device - clocksource

STMicroelectronics Low Power Controller (LPC) - RTC

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LPC currently supports Watchdog OR Real Time Clock functionality.

LPC currently supports Watchdog OR Real Time Clock OR Clocksource

functionality.

[See: ../watchdog/st_lpc_wdt.txt for Watchdog options]

[See: ../timer/st,stih407-lpc for Clocksource options]

Required properties

- compatible 	: Must be one of: "st,stih407-lpc" "st,stih416-lpc"

				  "st,stih415-lpc" "st,stid127-lpc"

- compatible 	: Must be: "st,stih407-lpc"

- reg		: LPC registers base address + size

- interrupts    : LPC interrupt line number and associated flags

- clocks	: Clock used by LPC device (See: ../clock/clock-bindings.txt)

- st,lpc-mode	: The LPC can run either one of two modes ST_LPC_MODE_RTC [0] or

		  ST_LPC_MODE_WDT [1].  One (and only one) mode must be

		  selected.

- st,lpc-mode	: The LPC can run either one of three modes:

                  ST_LPC_MODE_RTC    [0]

                  ST_LPC_MODE_WDT    [1]

                  ST_LPC_MODE_CLKSRC [2]

		 One (and only one) mode must be selected.

Example:

	lpc@fde05000 {