drm/i915/uc: Rename intel_uc_is_using* into intel_uc_supports*

Rename intel_uc_is_using* into intel_uc_supports* to make clear
distinction from actual state (compare intel_uc_fw_is_running)

Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@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/20190731223321.36436-2-michal.wajdeczko@intel.com