drm/amdgpu/pm: add capped/uncapped power profile modes

Capped and uncapped workload types switching are supported on Vangogh,
User can switch the power profile and check current type with below commands.

1) switch to capped mode:
`# echo 8 > /sys/class/drm/card0/device/pp_power_profile_mode`

2) switch to uncapped mode:
`# echo 9 > /sys/class/drm/card0/device/pp_power_profile_mode`

3) check current mode:
$ cat /sys/class/drm/card0/device/pp_power_profile_mode
 1 3D_FULL_SCREEN
 3          VIDEO
 4             VR
 5        COMPUTE
 6         CUSTOM
 8         CAPPED
 9       UNCAPPED*

Acked-by: Kenneth Feng <kenneth.feng@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Signed-off-by: Perry Yuan <perry.yuan@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>