drm/amd: Expose the FRU SMU I2C bus

Expose both SMU I2C buses. Some boards use the same bus for both the RAS
and FRU EEPROMs and others use different buses.  This enables the
additional I2C bus and sets the right buses to use for RAS and FRU EEPROM
access.

Cc: Roy Sun <Roy.Sun@amd.com>
Co-developed-by: Alex Deucher <Alexander.Deucher@amd.com>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
Reviewed-by: Alex Deucher <Alexander.Deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>