drm/i915/uc: Add intel_uc_fw_type_repr()

Some of the DRM_NOTE messages are just using "uC" without specifying
which uc they are related to. We can be more user friendly.

v2: moved to the header (Joonas)

Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>