drm/i915/guc: Make the GuC fw loading helper functions general

Rename some of the GuC fw loading code to make them more general. We
will utilise them for HuC loading as well.
     s/intel_guc_fw/intel_uc_fw/g
     s/GUC_FIRMWARE/INTEL_UC_FIRMWARE/g

Struct intel_guc_fw is renamed to intel_uc_fw. Prefix of tts members,
such as 'guc' or 'guc_fw' either is renamed to 'uc' or removed for
same purpose.

v2: rebased on top of nightly.
    reapplied the search/replace as upstream code as changed.
v3: removed G from messages in shared fw fetch function.
v4: rebased.Updated dev to dev_priv in intel_guc_setup(), guc_fw_getch()
and intel_guc_init().
v5: rebased. Remove uint32_t fw_type to patch 2. Add INTEL_ prefix for
fields in enum intel_uc_fw_status. Remove uc_dev field since its never
used.Rename uc_fw to just fw and guc_fw to fw to avoid redundency.
v6: rebased. Remove sections of code that were commented and no longer
required.
v7: rebased. Remove uc_fw_ prefix from path and obj fields
in intel_uc_fw struct as suggested by Michal.
v8: rebased. Add declaration of intel_guc_wopcm_size() in
this patch instead of patch 3.

Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Signed-off-by: Anusha Srivatsa <anusha.srivatsa@intel.com>
Signed-off-by: Alex Dai <yu.dai@intel.com>
Signed-off-by: Peter Antoine <peter.antoine@intel.com>
Reviewed-by: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1484356631-16139-2-git-send-email-anusha.srivatsa@intel.com