OMAP: DSS2: fix clock sources on error and uninit

DPI and DSI were not cleaning up the clock source in error or uninit
cases. Set the clock source back to PRCM.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/dpi.c b/drivers/video/omap2/dss/dpi.c
index 046ce08..dc698bd 100644
--- a/drivers/video/omap2/dss/dpi.c
+++ b/drivers/video/omap2/dss/dpi.c
@@ -83,8 +83,10 @@
 	dss_select_dispc_clk_source(dssdev->clocks.dispc.dispc_fclk_src);
 
 	r = dispc_set_clock_div(dssdev->manager->id, &dispc_cinfo);
-	if (r)
+	if (r) {
+		dss_select_dispc_clk_source(OMAP_DSS_CLK_SRC_FCK);
 		return r;
+	}
 
 	*fck = dsi_cinfo.dsi_pll_hsdiv_dispc_clk;
 	*lck_div = dispc_cinfo.lck_div;