drm/amd/pp: use soc15 common macros instead of vega10 specific

pp_soc15.h is vega10 specific. Update powerplay code to use soc15 common
macros defined in soc15_common.h.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Rex Zhu <Rex.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>