video: Move and rename DM_HX8238D option

This is actually a panel, not a video device. Rename the option, move it
into the right place and make it depend on PANEL.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/arm/mach-omap2/am33xx/Kconfig b/arch/arm/mach-omap2/am33xx/Kconfig
index 987ab36..25e97cf 100644
--- a/arch/arm/mach-omap2/am33xx/Kconfig
+++ b/arch/arm/mach-omap2/am33xx/Kconfig
@@ -95,7 +95,7 @@
 	select DM_SERIAL
 	select DM_GPIO
 	select DM_VIDEO
-	select DM_PANEL_HX8238D
+	select PANEL_HX8238D
 
 config TARGET_AM335X_SL50
 	bool "Support am335x_sl50"