Remove the variable clamshell_closed from the function
dcn10_align_pixel_clocks.
This was pointed by clang with the following warning:
drivers/gpu/drm/amd/amdgpu/../display/dc/dcn10/dcn10_hw_sequencer.c:2063:7:
warning: variable 'clamshell_closed' set but not used
[-Wunused-but-set-variable]
    bool clamshell_closed = false;
         ^
Signed-off-by: Maíra Canal <maira.canal@usp.br>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
        uint32_t embedded_pix_clk_100hz;
        uint16_t embedded_h_total;
        uint16_t embedded_v_total;
-       bool clamshell_closed = false;
        uint32_t dp_ref_clk_100hz =
                dc->res_pool->dp_clock_source->ctx->dc->clk_mgr->dprefclk_khz*10;
 
        if (dc->config.vblank_alignment_dto_params &&
                dc->res_pool->dp_clock_source->funcs->override_dp_pix_clk) {
-               clamshell_closed =
-                       (dc->config.vblank_alignment_dto_params >> 63);
                embedded_h_total =
                        (dc->config.vblank_alignment_dto_params >> 32) & 0x7FFF;
                embedded_v_total =