drm/i915/guc: Prefer intel_guc_is_submission_supported

No need to use intel_uc_supports_guc_submission(uc) as we
can directly use intel_guc_is_submission_supported(guc)

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20190804195052.31140-2-michal.wajdeczko@intel.com