drm/amd/display: Remove unused variables from dml_rq_dlg_get_dlg_params

Remove the variables dispclk_delay_subtotal and dppclk_delay_subtotal from
the function dml_rq_dlg_get_dlg_params.

This was pointed by clang with the following warning:

drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn31/display_rq_dlg_calc_31.c:920:15:
warning: variable 'dispclk_delay_subtotal' set but not used [-Wunused-but-set-variable]
        unsigned int dispclk_delay_subtotal;
                     ^
drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn31/display_rq_dlg_calc_31.c:919:15:
warning: variable 'dppclk_delay_subtotal' set but not used [-Wunused-but-set-variable]
        unsigned int dppclk_delay_subtotal;
                     ^
2 warnings 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>