drm/amd/display/dc/dce/dce_stream_encoder: Remove unused variable 'regval'

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

 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_stream_encoder.c: In function ‘dce110_update_generic_info_packet’:
 drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_stream_encoder.c:70:11: warning: variable ‘regval’ set but not used [-Wunused-but-set-variable]

Cc: Harry Wentland <harry.wentland@amd.com>
Cc: Leo Li <sunpeng.li@amd.com>
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: George Shen <george.shen@amd.com>
Cc: Eric Bernstein <eric.bernstein@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/dce/dce_stream_encoder.c

@@ -67,7 +67,6 @@ static void dce110_update_generic_info_packet(
 	uint32_t packet_index,
 	const struct dc_info_packet *info_packet)
 {
-	uint32_t regval;
 	/* TODOFPGA Figure out a proper number for max_retries polling for lock
 	 * use 50 for now.
 	 */
@@ -99,7 +98,7 @@ static void dce110_update_generic_info_packet(
 	}
 	/* choose which generic packet to use */
 	{
-		regval = REG_READ(AFMT_VBI_PACKET_CONTROL);
+		REG_READ(AFMT_VBI_PACKET_CONTROL);
 		REG_UPDATE(AFMT_VBI_PACKET_CONTROL,
 				AFMT_GENERIC_INDEX, packet_index);
 	}