clk: st: Support for ClockGenA9/DDR/GPU

The patch added support for DT registration of ClockGenA9/DDR/GPU

ClockgenA9/DDR : It includes c32 type PLL (also in ClockgenA1x), hence
only CLK_OF_DECLARE implementation is required.

ClockgenGPU : It includes c65 type PLL (also in ClockgenAx), hence
only CLK_OF_DECLARE implementation is required.

Signed-off-by: Pankaj Dev <pankaj.dev@st.com>
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@st.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>