video: mxsfb: add clk_enable()

BROM doesn't enable lcdif by default so add clk_enable() after
clk_set_rate().

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
Reviewed-by: Anatolij Gustschin <agust@denx.de>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
diff --git a/drivers/video/mxsfb.c b/drivers/video/mxsfb.c
index 8a5a61c..12d00b4 100644
--- a/drivers/video/mxsfb.c
+++ b/drivers/video/mxsfb.c
@@ -77,6 +77,12 @@
 		dev_err(dev, "Failed to set mxs clk: %d\n", ret);
 		return;
 	}
+
+	ret = clk_enable(&per_clk);
+	if (ret < 0) {
+		dev_err(dev, "Failed to enable mxs clk: %d\n", ret);
+		return;
+	}
 #else
 	/* Kick in the LCDIF clock */
 	mxs_set_lcdclk(MXS_LCDIF_BASE, timings->pixelclock.typ / 1000);