clk: ti: Remove AM33xx dependency

clk: ti: Remove AM33xx dependency

The clock controller driven by this driver exists on other OMAP platforms
than the AM33xx. Yet, it uses functions provided by
arch/arm/mach-omap2/am33xx/clock.c making it unusable by other OMAPs.

Replace am33xx-specific do_{enable/disable}_clocks() with new static
functions implemented locally.
Replace the am33xx-specific clock header with the one shared by all OMAP
platforms.

Signed-off-by: Bastien Curutchet <bastien.curutchet@bootlin.com>