dm: video: show correct colors in graphical console

dm: video: show correct colors in graphical console

Get RGB sequence in pixels right (swap blue and red).
Do not set reserved bits.

qemu-system-i386 -display sdl -vga virtio and
qemu-system-i386 -display sdl -vga cirrus
now display the similar colors (highlighting still missing) as
qemu-system-i386 -nographic

Testing is possible via

	setenv efi_selftest test output
	bootefi selftest

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>