video: bpp16: Disable by default on sunXi

The sunXi arm64 build has overflown, leading to the main U-boot binary
overwriting the environment when flashing the new image, or even worse,
overwriting itself when we're calling saveenv.

Disable this command that is not critical until we can adress the issue
properly.
Reviewed-by: NAnatolij Gustschin <agust@denx.de>
Reviewed-by: NAndre Przywara <andre.przywara@arm.com>
Signed-off-by: NMaxime Ripard <maxime.ripard@free-electrons.com>
Reviewed-by: NJagan Teki <jagan@openedev.com>

drivers/video/Kconfig

@@ -49,6 +49,7 @@ config VIDEO_BPP8
 config VIDEO_BPP16
 	bool "Support 16-bit-per-pixel displays"
 	depends on DM_VIDEO
+	default n if ARCH_SUNXI
 	default y if DM_VIDEO
 	help
 	  Support drawing text and bitmaps onto a 16-bit-per-pixel display.