drm/amd/display: Reapply 2fde4fdddc1f

drm/amd/display: Reapply 2fde4fdddc1f

Commit 2563391e57b5 ("drm/amd/display: DML2.1 resynchronization") blew
away the compiler warning fix from commit 2fde4fdddc1f
("drm/amd/display: Avoid -Wenum-float-conversion in
add_margin_and_round_to_dfs_grainularity()"), causing the warning to
reappear.

  drivers/gpu/drm/amd/amdgpu/../display/dc/dml2/dml21/src/dml2_dpmm/dml2_dpmm_dcn4.c:183:58: error: arithmetic between enumeration type 'enum dentist_divider_range' and floating-point type 'double' [-Werror,-Wenum-float-conversion]
    183 |         divider = (unsigned int)(DFS_DIVIDER_RANGE_SCALE_FACTOR * (vco_freq_khz / clock_khz));
        |                                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ^ ~~~~~~~~~~~~~~~~~~~~~~~~~~
  1 error generated.

Apply the fix again to resolve the warning.

Fixes: 1b30456150e5 ("drm/amd/display: DML21 Reintegration")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>