clk: ti: add generic support for clock latching

Certain clocks require latching to be done, so that the actual
settings get updated on the HW that generates the clock signal.
One example of such a clock is the dra76x GMAC DPLL H14 output,
which requires its divider settings to be latched when updated.

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