omap: GPIO: fix auto-disable of debounce clock

The addition of the new debounce code (commit
168ef3d) broke the auto-disable of
debounce clocks on idle by forgetting to update the debounce clock
enable mask.

Add back the updating of bank->dbck_enable_mask so debounce clocks are
auto-disabled.

Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/plat-omap/gpio.c

@@ -673,6 +673,7 @@ static void _set_gpio_debounce(struct gpio_bank *bank, unsigned gpio,
 		if (cpu_is_omap34xx() || cpu_is_omap44xx())
 			clk_disable(bank->dbck);
 	}
+	bank->dbck_enable_mask = val;
 
 	__raw_writel(val, reg);
 }