feat(st-uart): add initialization with the device tree

Add the pincontrol configuration and clock enable in UART driver
with information found in the device tree.

This patch avoids an issue on STM32MP13x platform because the UART
configuration is reset by the ROM code for UART serial boot

Signed-off-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Change-Id: I575fd0e1026b857059abcfd4a3166eb3a239e1fd
1 file changed