video: Add a test for 16bpp BMP files

Add a compressed 16bpp BMP file and a test to cover this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/.gitattributes b/.gitattributes
index 899473a..1879a2d 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -3,3 +3,4 @@
 # Denote all files that are truly binary and should not be modified
 *.bmp binary
 *.ttf binary
+*.gz binary