ARM: mxc: arch_reset: add clk_prepare/clk_unprepare

It's for migrating to generic clk framework API.
Signed-off-by: Richard Zhao <richard.zhao@linaro.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

arch/arm/plat-mxc/system.c

@@ -48,7 +48,7 @@ void mxc_restart(char mode, const char *cmd)
 
 		clk = clk_get_sys("imx2-wdt.0", NULL);
 		if (!IS_ERR(clk))
-			clk_enable(clk);
+			clk_prepare_enable(clk);
 		wcr_enable = (1 << 2);
 	}