gpio: omap: prepare and unprepare the debounce clock

Replace the clk_enable()s with a clk_prepare_enable() and
the clk_disables()s with a clk_disable_unprepare()

This never showed issues due to the OMAP platform code (hwmod)
leaving these clocks in clk_prepare()ed state by default.

Reported-by: Kishon Vijay Abraham I <[e-mail]>
Signed-off-by: Rajendra Nayak <[e-mail]>
Acked-by: Javier Martinez Canillas <[e-mail]>
Acked-by: Santosh Shilimkar <[e-mail]>
Cc: Kevin Hilman <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpio-omap.c

···
 static inline void _gpio_dbck_enable(struct gpio_bank *bank)
 {
 	if (bank->dbck_enable_mask && !bank->dbck_enabled) {
-		clk_enable(bank->dbck);
+		clk_prepare_enable(bank->dbck);
 		bank->dbck_enabled = true;
 
 		writel_relaxed(bank->dbck_enable_mask,
···
 		 */
 		writel_relaxed(0, bank->base + bank->regs->debounce_en);
 
-		clk_disable(bank->dbck);
+		clk_disable_unprepare(bank->dbck);
 		bank->dbck_enabled = false;
 	}
 }
···
 
 	l = GPIO_BIT(bank, gpio);
 
-	clk_enable(bank->dbck);
+	clk_prepare_enable(bank->dbck);
 	reg = bank->base + bank->regs->debounce;
 	writel_relaxed(debounce, reg);
 
···
 	bank->dbck_enable_mask = val;
 
 	writel_relaxed(val, reg);
-	clk_disable(bank->dbck);
+	clk_disable_unprepare(bank->dbck);
 	/*
 	 * Enable debounce clock per module.
 	 * This call is mandatory because in omap_gpio_request() when
···
 		bank->context.debounce = 0;
 		writel_relaxed(bank->context.debounce, bank->base +
 			     bank->regs->debounce);
-		clk_disable(bank->dbck);
+		clk_disable_unprepare(bank->dbck);
 		bank->dbck_enabled = false;
 	}
 }