drm/i915/fbc: Remove pointless "stride is multiple of 64 bytes" check

Plane stride is always a multiple of 64 bytes. Remove the
pointless check that really doesn't have anything to do
with FBC.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231003194256.28569-6-ville.syrjala@linux.intel.com


Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>