uboot-imx

stm32mp1: clk: add LDTC and DSI clock support

This patch add clk_enable/clk_disable/clk_get_rate support for
- DSI_PX
- LTDC_PX
- DSI_K (only get rate)

These clocks are needed for LTDC and DSI drivers with latest device tree.

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>