drm/amd/powerplay: add the hw manager for vega20 (v3)

hwmgr is the interface for the driver to setup state
structures which are used by the smu for managing the
power state.

v2: squash in fixes:
- update set_watermarks_for_clocks_ranges to use common code
- drop unsupported apis
- correct MAX_REGULAR_DPM_NUMBER value
- multimonitor fixes
- add check for vbios pptable version
- revise dpm table setup
- init fclk dpm state
- Remove unused definition in vega20_hwmgr
- support power limit setup
- enable vega20 to honour DAL clock limits
- comment out dump_table debugging
v3: switch to SOC15 register access macros

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>