lcd: Implement RLE8 bitmap decoding

Add support for drawing compressed RLE8 bitmaps.

Reference: http://www.digicamsoft.com/bmp/bmp.html



Signed-off-by: Che-Liang Chiou <clchiou@chromium.org>
Signed-off-by: Tom Wai-Hong Tam <waihong@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Che-Liang Chiou <clchiou@chromium.org>
[agust: fix some minor style issues and build warnings]
Signed-off-by: Anatolij Gustschin <agust@denx.de>