drm/amd/display: Remove unused clk_src variable

Remove the variable clk_src from the function dcn3_get_pix_clk_dividers.

This was pointed by clang with the following warning:

drivers/gpu/drm/amd/amdgpu/../display/dc/dce/dce_clock_source.c:1279:25: warning:
variable 'clk_src' set but not used [-Wunused-but-set-variable]
        struct dce110_clk_src *clk_src;
                               ^
1 warning generated.
Reviewed-by: André Almeida <andrealmeid@igalia.com>
Signed-off-by: Maíra Canal <mairacanal@riseup.net>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -1276,9 +1276,7 @@ static uint32_t dcn3_get_pix_clk_dividers(
 		struct pll_settings *pll_settings)
 {
 	unsigned long long actual_pix_clk_100Hz = pix_clk_params ? pix_clk_params->requested_pix_clk_100hz : 0;
-	struct dce110_clk_src *clk_src;
 
-	clk_src = TO_DCE110_CLK_SRC(cs);
 	DC_LOGGER_INIT();
 
 	if (pix_clk_params == NULL || pll_settings == NULL