clk: ti: Split common omap2plus functions into new symbol

clk: ti: Split common omap2plus functions into new symbol

Create a new symbol for the common clock functions used by some of the
omap2plus clock drivers. These drivers now select this new symbol when
they need the functions. Note these common functions are not
ARCH_OMAP2PLUS specific.

Note that the common functions are using regmap, so select it here.

Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Markus Schneider-Pargmann (TI.com) <msp@baylibre.com>