Also ajust the gfx domain voltage on Tonga when user overdriver
the voltage.

For Tonga, Driver do not update user's setting to voltage table
in smu, we only pick up a minimum value from voltage table that
not less than the user's setting.

v2: fix a typo
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>