drm/amd/display/dc/gpio/hw_ddc: Remove unused variable 'reg2'

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

 drivers/gpu/drm/amd/amdgpu/../display/dc/gpio/hw_ddc.c: In function ‘set_config’:
 drivers/gpu/drm/amd/amdgpu/../display/dc/gpio/hw_ddc.c:110:13: warning: variable ‘reg2’ 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: 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/gpio/hw_ddc.c

@@ -107,11 +107,10 @@ static enum gpio_result set_config(
 					msleep(3);
 			}
 		} else {
-			uint32_t reg2;
 			uint32_t sda_pd_dis = 0;
 			uint32_t scl_pd_dis = 0;
 
-			reg2 = REG_GET_2(gpio.MASK_reg,
+			REG_GET_2(gpio.MASK_reg,
 				  DC_GPIO_SDA_PD_DIS, &sda_pd_dis,
 				  DC_GPIO_SCL_PD_DIS, &scl_pd_dis);