fbdev: sh_mobile_meram: Fix MExxCTL register save on runtime PM suspend

To reset the ICB on resume the MExxCTL register needs to be OR'ed with
MExxCTL_WBF | MExxCTL_WF | MExxCTL_RF, no set to that value. Fix this.

This fixes corruption at the bottom of the display when resuming from
runtime PM.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

drivers/video/sh_mobile_meram.c

@@ -549,7 +549,7 @@ static int sh_mobile_meram_runtime_suspend(struct device *dev)
 				meram_read_icb(priv->base, j, icb_regs[k]);
 			/* Reset ICB on resume */
 			if (icb_regs[k] == MExxCTL)
-				priv->icb_saved_regs[j * ICB_REGS_SIZE + k] =
+				priv->icb_saved_regs[j * ICB_REGS_SIZE + k] |=
 					MExxCTL_WBF | MExxCTL_WF | MExxCTL_RF;
 		}
 	}