x86: fsp: graphics: Add some notes about the graphics info hob

On some platforms (eg: Braswell), the FSP will not produce the
graphics info HOB unless you plug some cables to the display
interface (eg: HDMI) on the board. Add such notes in the FSP
video driver.
Signed-off-by: NBin Meng <bmeng.cn@gmail.com>
Reviewed-by: NSimon Glass <sjg@chromium.org>

arch/x86/lib/fsp/fsp_graphics.c

@@ -37,6 +37,10 @@ static int save_vesa_mode(struct vesa_mode_info *vesa)
 	/*
 	 * If there is no graphics info structure, bail out and keep
 	 * running on the serial console.
+	 *
+	 * Note: on some platforms (eg: Braswell), the FSP will not produce
+	 * the graphics info HOB unless you plug some cables to the display
+	 * interface (eg: HDMI) on the board.
 	 */
 	if (!ginfo) {
 		debug("FSP graphics hand-off block not found\n");