CLK: TI: add omap3 clock init file

clk-3xxx.c now contains the clock init functionality for omap3, including
DT clock registration and adding of static clkdev entries.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Tested-by: Nishanth Menon <nm@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>