drm/kmb: Fix build warnings

Fixed the following W=1 kernel build warnings
 drivers/gpu/drm/kmb/kmb_plane.h:74:18: warning: ‘kmb_formats_v’
 defined but not used [-Wunused-const-variable=]
 drivers/gpu/drm/kmb/kmb_plane.h:61:18: warning: ‘kmb_formats_g’
 defined but not used [-Wunused-const-variable=]

Signed-off-by: Anitha Chrisanthus <anitha.chrisanthus@intel.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1605045169-2696-1-git-send-email-anitha.chrisanthus@intel.com