clk: stm32mp13: Add SPL support and clock tree init to STM32MP13 RCC driver

clk: stm32mp13: Add SPL support and clock tree init to STM32MP13 RCC driver

Add SPL support and clock tree init to STM32MP13 RCC driver. This
consists of two parts, make SCMI into an optional dependency and
add clock tree initialization. The SCMI dependency is made optional
first by registering the few core clock provided by SCMI clock as
fixed clock, and second by letting the clock core parse out the
clock configuration from SoC registers. The clock initialization
code is derived from STM32MP15xx clock tree initialization code,
which is almost identical, except for the use of new PLL2000 for
PLL1 on STM32MP13xx .

Signed-off-by: Marek Vasut <marek.vasut@mailbox.org>