clk: ti: clkdm: move clkdm gate clock support code to clock driver

clk: ti: clkdm: move clkdm gate clock support code to clock driver

With the legacy clock data gone, this is no longer needed under platform,
so move it under the clock driver itself. Remove the exported clock driver
APIs as well, as these are not needed outside clock driver anymore.

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