OMAPDSS: remove dssdev uses in trivial cases

In the future the "dssdev" parameter passed to output drivers will
change its meaning. Instead of being a pointer to the panel device, it's
a pointer to the output instance.

To make the transition easier, some of the uses for this dssdev
parameter can be easily removed.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/drivers/video/omap2/dss/venc.c b/drivers/video/omap2/dss/venc.c
index a06c860..f6d2b3f 100644
--- a/drivers/video/omap2/dss/venc.c
+++ b/drivers/video/omap2/dss/venc.c
@@ -429,7 +429,7 @@
 
 static int venc_power_on(struct omap_dss_device *dssdev)
 {
-	struct omap_overlay_manager *mgr = dssdev->output->manager;
+	struct omap_overlay_manager *mgr = venc.output.manager;
 	u32 l;
 	int r;
 
@@ -480,7 +480,7 @@
 
 static void venc_power_off(struct omap_dss_device *dssdev)
 {
-	struct omap_overlay_manager *mgr = dssdev->output->manager;
+	struct omap_overlay_manager *mgr = venc.output.manager;
 
 	venc_write_reg(VENC_OUTPUT_CONTROL, 0);
 	dss_set_dac_pwrdn_bgz(0);
@@ -500,7 +500,7 @@
 
 int omapdss_venc_display_enable(struct omap_dss_device *dssdev)
 {
-	struct omap_dss_output *out = dssdev->output;
+	struct omap_dss_output *out = &venc.output;
 	int r;
 
 	DSSDBG("venc_display_enable\n");