rockchip: video: Lower hpd wait time

Waiting 30 seconds for the hpd to go high seems a bit much, especially
on headless boots. Lowering the timeout to 300ms.

Sending as RFC because frankly i don't know what a sensible timeout is
here, but 30 seconds is clearly not it :)

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Reviewed-by: Simon Glass <sjg@chromium.org>
Dropped RFC tag:
Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/video/rockchip/rk_hdmi.c

@@ -666,7 +666,7 @@ static int hdmi_wait_for_hpd(struct rk3288_hdmi *regs)
 		if (hdmi_get_plug_in_status(regs))
 			return 0;
 		udelay(100);
-	} while (get_timer(start) < 30000);
+	} while (get_timer(start) < 300);
 
 	return -1;
 }