UPSTREAM: fbmem: Check virtual screen sizes in fb_set_var()

commit 6c11df58 upstream.

Verify that the fbdev or drm driver correctly adjusted the virtual
screen sizes. On failure report the failing driver and reject the screen
size change.

Signed-off-by: Helge Deller <deller@gmx.de>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Bug: 240019719
Signed-off-by: Todd Kjos <tkjos@google.com>
Change-Id: I70ed1cf3d0f169db8383a9e221f9f4388a69c5d6
Signed-off-by: Lee Jones <joneslee@google.com>