OMAP2, 3: DSS2: VENC: create platform_driver, move init, exit to driver

Hwmod adaptation design requires each of the DSS HW IP to be a platform driver.
So a platform_driver for VENC is created and init exit methods are moved from core.c
to its driver probe,remove. pdev member has to be maintained by its own drivers.

Also, venc_vdda_dac reading is moved to venc.c.

VENC platform driver is registered from inside omap_dss_probe, in the order desired.

Signed-off-by: Senthilvadivu Guruswamy <svadivu@ti.com>
Signed-off-by: Sumit Semwal <sumit.semwal@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

arch/arm/mach-omap2/board-zoom-peripherals.c

@@ -230,7 +230,7 @@ static struct regulator_consumer_supply zoom_vpll2_supply =
 	REGULATOR_SUPPLY("vdds_dsi", "omapdss");
 
 static struct regulator_consumer_supply zoom_vdda_dac_supply =
-	REGULATOR_SUPPLY("vdda_dac", "omapdss");
+	REGULATOR_SUPPLY("vdda_dac", "omapdss_venc");
 
 static struct regulator_init_data zoom_vpll2 = {
 	.constraints = {