video: Use 'int' for loop variables instead of short

Using short doesn't save anything and is confusing when the width and height
variables are ulong.

This may fix Coverity CID134902 but I doubt it.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

drivers/video/video_bmp.c

@@ -194,7 +194,7 @@ int video_bmp_display(struct udevice *dev, ulong bmp_image, int x, int y,
 {
 	struct video_priv *priv = dev_get_uclass_priv(dev);
 	ushort *cmap_base = NULL;
-	ushort i, j;
+	int i, j;
 	uchar *fb;
 	struct bmp_image *bmp = map_sysmem(bmp_image, 0);
 	uchar *bmap;