drm/radeon/cik: Remove set but unused variable 'mc_shared_chmap'

Fixes the following W=1 kernel build warning(s):

 drivers/gpu/drm/radeon/cik.c: In function ‘cik_gpu_init’:
 drivers/gpu/drm/radeon/cik.c:3180:6: warning: variable ‘mc_shared_chmap’ set but not used [-Wunused-but-set-variable]

Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/radeon/cik.c

@@ -3177,7 +3177,7 @@ static void cik_setup_rb(struct radeon_device *rdev,
 static void cik_gpu_init(struct radeon_device *rdev)
 {
 	u32 gb_addr_config = RREG32(GB_ADDR_CONFIG);
-	u32 mc_shared_chmap, mc_arb_ramcfg;
+	u32 mc_arb_ramcfg;
 	u32 hdp_host_path_cntl;
 	u32 tmp;
 	int i, j;
@@ -3270,7 +3270,7 @@ static void cik_gpu_init(struct radeon_device *rdev)
 
 	WREG32(BIF_FB_EN, FB_READ_EN | FB_WRITE_EN);
 
-	mc_shared_chmap = RREG32(MC_SHARED_CHMAP);
+	RREG32(MC_SHARED_CHMAP);
 	mc_arb_ramcfg = RREG32(MC_ARB_RAMCFG);
 
 	rdev->config.cik.num_tile_pipes = rdev->config.cik.max_tile_pipes;