clk: stm32: add support compatible st, stm32mp1-rcc-secure

Add support for new compatible st,stm32mp1-rcc-secure used when the
RCC resource is managed by secured world (RCC_TZCR.TZEN=1)
iand when SCMI is used.

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Reviewed-by: Patrice Chotard <patrice.chotard@foss.st.com>