clk: add support for TI K3 SoC clocks

Add driver to support TI K3 generation SoC clocks. This driver registers
the clocks provided via platform data, and adds support for controlling
the clocks via DT handles.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tero Kristo <kristo@kernel.org>