video: Add a function to get the dimensions of a BMP image

This is useful for some other users, so break this out into a function.

Signed-off-by: Simon Glass <sjg@chromium.org>

include/video.h

@@ -223,6 +223,17 @@ int video_sync(struct udevice *vid, bool force);
  */
 void video_sync_all(void);
 
+/**
+ * video_bmp_get_info() - Get information about a bitmap image
+ *
+ * @bmp_image: Pointer to BMP image to check
+ * @widthp: Returns width in pixels
+ * @heightp: Returns height in pixels
+ * @bpixp: Returns log2 of bits per pixel
+ */
+void video_bmp_get_info(void *bmp_image, ulong *widthp, ulong *heightp,
+			uint *bpixp);
+
 /**
  * video_bmp_display() - Display a BMP file
  *