Check for Overflow bits for layer3 in the irq handler.

Fixes: 7f7b96a8 ("drm/kmb: Add support for KeemBay Display")
Signed-off-by: Anitha Chrisanthus <anitha.chrisanthus@intel.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20211013233632.471892-5-anitha.chrisanthus@intel.comSigned-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>