ARM: OMAP2+: clock: remove clkdm_control static boolean from code

clkdm_control is used to determine, whether clocks should trigger a
clockdomain transition when they are enabled/disabled. Keep this
functionality intact, but replace this with a clk_features flag
which can be initialized during boot if needed.

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