OMAP: GPIO: ensure debounce clocks are disabled during idle/suspend

If a GPIO bank has more than one GPIO with debounce enabled, the
debounce clock will not be fully disabled before going to
idle/suspend.

In the idle path, we just do a single clk_disable() of the bank's
debounce clock.  If there are multiple debounce-enabled GPIOs in the
bank, that clocks usage count will be > 1, so the clk_disable() will
not actually disable the clock.

So the fix is to clk_disable() for every debounce-enabled GPIO in the
bank (and an equivalent clk_enable() of course.)

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>