dts/arm/st: l5: Add clocks node to stm32l5.dtsi

Add clocks node and clocks to stm32l5 series.
PLL binding is reused from stm32l4 series.
Matching binding is updated to document that.

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>
2 files changed