drm/i915/huc: Unified css_header struct for GuC and HuC

HuC firmware css header has almost exactly same definition as GuC
firmware except for the sw_version. Also, add a new member fw_type
into intel_uc_fw to indicate what kind of fw it is. So, the loader
will pull right sw_version from header.

v2: rebased on-top of drm-intel-nightly
v3: rebased. Rename device_id to guc_branch_client_version,
make guc_sw_version a union. <Jeff Mcgee>. Put UC_FW_TYPE_GUC
and UC_FW_TYPE_HUC into an enum.
v4: rebased on top of drm-tip.Update dev to dev_priv in
intel_uc_fw_fetch.
v5: rebased. Add INTEL_ prefix to an enum. Add fw_type declaration
from patch 1.Combine two different unions for huc and guc version,
reserved etc into one union with two structs.
v6: rebased. Change fw_type to enum.
v7: rebased. Rename the enum fw_type to intel_uc_fw_type.

Cc: Michal Wajdeczko <michal.wajdeczko.@intel.com>
Tested-by: Xiang Haihao <haihao.xiang@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/1484356631-16139-3-git-send-email-anusha.srivatsa@intel.com