drm/amd/powerplay: fix a typo

Util -> Until

Fixes: 567c8fc4 ("drm/amd/powerplay: implement the is_dpm_running()")
Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>