video: mxsfb: add enabling of "disp_axi" clock

Some SoC needs "disp_axi" clock to be enabled, so let's try to retrieve it
and enabling. If it fails it gives only a debug(), but this clock as well
as "axi" clock is not mandatory.

Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
diff --git a/drivers/video/mxsfb.c b/drivers/video/mxsfb.c
index 147bd66..523d8a8 100644
--- a/drivers/video/mxsfb.c
+++ b/drivers/video/mxsfb.c
@@ -98,6 +98,17 @@
 			return;
 		}
 	}
+
+	ret = clk_get_by_name(dev, "disp_axi", &clk);
+	if (!ret) {
+		debug("%s: Failed to get mxs disp_axi clk: %d\n", __func__, ret);
+	} else {
+		ret = clk_enable(&clk);
+		if (ret < 0) {
+			dev_err(dev, "Failed to enable mxs disp_axi clk: %d\n", ret);
+			return;
+		}
+	}
 #else
 	/* Kick in the LCDIF clock */
 	mxs_set_lcdclk(MXS_LCDIF_BASE, timings->pixelclock.typ / 1000);