gpio/omap: fix debounce clock handling

The dbck_enable_mask indicates which all GPIOs within a bank have debounce
enabled and dbck is enabled/disabled based upon this. But there is no
mechanism to track the dbck state. In order to manage the dbck state we need
additional flag and logic so that turning off/on dbck is synchronized with
pm_runtime_put/get_sync calls.

Signed-off-by: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>