drm/kmb: Limit supported mode to 1080p

drm/kmb: Limit supported mode to 1080p

KMB only supports single resolution(1080p), this commit checks for
1920x1080x60 or 1920x1080x59 in crtc_mode_valid.
Also, modes with vfp < 4 are not supported in KMB display. This change
prunes display modes with vfp < 4.

v2: added vfp check

Fixes: 7f7b96a8a0a1 ("drm/kmb: Add support for KeemBay Display")
Co-developed-by: Edmund Dea <edmund.j.dea@intel.com>
Signed-off-by: Edmund Dea <edmund.j.dea@intel.com>
Signed-off-by: Anitha Chrisanthus <anitha.chrisanthus@intel.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link:https://patchwork.freedesktop.org/patch/msgid/20211013233632.471892-2-anitha.chrisanthus@intel.com
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>