video: mxsfb: convert to clk_prepare/clk_unprepare

The patch converts mxsfb 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>
Acked-by: Marek Vasut <marek.vasut@gmail.com>
Acked-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>

drivers/video/mxsfb.c

@@ -328,7 +328,7 @@ static void mxsfb_enable_controller(struct fb_info *fb_info)
 
 	dev_dbg(&host->pdev->dev, "%s\n", __func__);
 
-	clk_enable(host->clk);
+	clk_prepare_enable(host->clk);
 	clk_set_rate(host->clk, PICOS2KHZ(fb_info->var.pixclock) * 1000U);
 
 	/* if it was disabled, re-enable the mode again */
@@ -368,7 +368,7 @@ static void mxsfb_disable_controller(struct fb_info *fb_info)
 
 	writel(VDCTRL4_SYNC_SIGNALS_ON, host->base + LCDC_VDCTRL4 + REG_CLR);
 
-	clk_disable(host->clk);
+	clk_disable_unprepare(host->clk);
 
 	host->enabled = 0;
 }
@@ -668,7 +668,7 @@ static int __devinit mxsfb_restore_mode(struct mxsfb_info *host)
 	line_count = fb_info->fix.smem_len / fb_info->fix.line_length;
 	fb_info->fix.ypanstep = 1;
 
-	clk_enable(host->clk);
+	clk_prepare_enable(host->clk);
 	host->enabled = 1;
 
 	return 0;
@@ -841,7 +841,7 @@ static int __devinit mxsfb_probe(struct platform_device *pdev)
 
 error_register:
 	if (host->enabled)
-		clk_disable(host->clk);
+		clk_disable_unprepare(host->clk);
 	fb_destroy_modelist(&fb_info->modelist);
 error_init_fb:
 	kfree(fb_info->pseudo_palette);