drm/amd/display: cleanup inconsistent indenting in amdgpu_dm_color

smatch warnings:
amdgpu_dm_update_plane_color_mgmt() warn: inconsistent indenting
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202401051643.PPdbmG1U-lkp@intel.com/Signed-off-by: Melissa Wen <mwen@igalia.com>
Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>