drm/radeon: add initial ucode loading for CIK (v5)

Currently the driver required 6 sets of ucode:
1. pfp - pre-fetch parser, part of the GFX CP
2. me - micro engine, part of the GFX CP
3. ce - constant engine, part of the GFX CP
4. rlc - interrupt, etc. controller
5. mc - memory controller (discrete cards only)
6. mec - compute engines, part of Compute CP

V2: add documentation
V3: update MC ucode
V4: rebase
V5: update mc ucode

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index b1a2230..1c06c47 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -1714,6 +1714,7 @@
 	const struct firmware *mc_fw;	/* NI MC firmware */
 	const struct firmware *ce_fw;	/* SI CE firmware */
 	const struct firmware *uvd_fw;	/* UVD firmware */
+	const struct firmware *mec_fw;	/* CIK MEC firmware */
 	struct r600_blit r600_blit;
 	struct r600_vram_scratch vram_scratch;
 	int msi_enabled; /* msi enabled */