drm/radeon/dpm: add support for SVI2 voltage for SI

Some newer boards use SVI2 for voltage control rather
than GPIO.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --cc drivers/gpu/drm/radeon/radeon.h
Simple merge

diff --cc drivers/gpu/drm/radeon/radeon_atombios.c
Simple merge

diff --cc drivers/gpu/drm/radeon/si_dpm.c
Simple merge

diff --cc drivers/gpu/drm/radeon/si_dpm.h
Simple merge

diff --cc drivers/gpu/drm/radeon/sislands_smc.h
Simple merge