drm/kmb: Build files for KeemBay Display driver

v2: Added Maintainer entry
v3: Added one more Maintainer entry
v3: drop videomode_helpers

Cc: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Anitha Chrisanthus <anitha.chrisanthus@intel.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1604538931-26726-8-git-send-email-anitha.chrisanthus@intel.com