serial: mxs-auart: convert to clk_prepare/clk_unprepare

The patch converts mxs-auart driver to clk_prepare/clk_unprepare by
using helper functions clk_prepare_enable/clk_disable_unprepare.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Alan Cox <alan@linux.intel.com>

drivers/tty/serial/mxs-auart.c

@@ -424,7 +424,7 @@ static int mxs_auart_startup(struct uart_port *u)
 {
 	struct mxs_auart_port *s = to_auart_port(u);
 
-	clk_enable(s->clk);
+	clk_prepare_enable(s->clk);
 
 	writel(AUART_CTRL0_CLKGATE, u->membase + AUART_CTRL0_CLR);
 
@@ -453,7 +453,7 @@ static void mxs_auart_shutdown(struct uart_port *u)
 	writel(AUART_INTR_RXIEN | AUART_INTR_RTIEN | AUART_INTR_CTSMIEN,
 			u->membase + AUART_INTR_CLR);
 
-	clk_disable(s->clk);
+	clk_disable_unprepare(s->clk);
 }
 
 static unsigned int mxs_auart_tx_empty(struct uart_port *u)
@@ -634,7 +634,7 @@ auart_console_setup(struct console *co, char *options)
 	if (!s)
 		return -ENODEV;
 
-	clk_enable(s->clk);
+	clk_prepare_enable(s->clk);
 
 	if (options)
 		uart_parse_options(options, &baud, &parity, &bits, &flow);
@@ -643,7 +643,7 @@ auart_console_setup(struct console *co, char *options)
 
 	ret = uart_set_options(&s->port, co, baud, parity, bits, flow);
 
-	clk_disable(s->clk);
+	clk_disable_unprepare(s->clk);
 
 	return ret;
 }