feat(clk): add a minimal clock framework

This is mainly a clock interface with clk_ops callbacks.
Those callbacks are: enable, disable, get_rate, set_parent,
and is_enabled.
This framework is compiled for STM32MP1.

Change-Id: I5119a2aeaf103ceaae7a60d9e423caf0c148d794
Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@st.com>
3 files changed