sunxi: video: select dw-hdmi in Kconfig, not Makefile

Currently sunxi Makefile manually specifies full path to dw-hdmi common
code. However, that is not needed because it can be selected in Kconfig
instead.

Select proper symbol in Kconfig and drop path from Makefile.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/arch/arm/mach-sunxi/Kconfig b/arch/arm/mach-sunxi/Kconfig
index a29d115..8e9012d 100644
--- a/arch/arm/mach-sunxi/Kconfig
+++ b/arch/arm/mach-sunxi/Kconfig
@@ -973,6 +973,7 @@
 	depends on SUNXI_DE2
 	select DM_VIDEO
 	select DISPLAY
+	select VIDEO_DW_HDMI
 	imply VIDEO_DT_SIMPLEFB
 	default y
 	---help---