efifb: BGRT: Add check for new BGRT status field rotation bits

Starting with ACPI 6.2 bits 1 and 2 of the BGRT status field are no longer
reserved. These bits are now used to indicate if the image needs to be
rotated before being displayed.

The efifb code does not support rotating the image before copying it to
the screen.

This commit adds a check for these new bits and if they are set leaves the
fb contents as is instead of trying to use the un-rotated BGRT image.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Peter Jones <pjones@redhat.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

drivers/video/fbdev/efifb.c

@@ -169,6 +169,11 @@ static void efifb_show_boot_graphics(struct fb_info *info)
 		return;
 	}
 
+	if (bgrt_tab.status & 0x06) {
+		pr_info("efifb: BGRT rotation bits set, not showing boot graphics\n");
+		return;
+	}
+
 	/* Avoid flashing the logo if we're going to print std probe messages */
 	if (console_loglevel > CONSOLE_LOGLEVEL_QUIET)
 		return;