drm/amd/amdgpu: add power profile sysfs entry

Add the sysfs entries pp_gfx_power_profile and
pp_compute_power_profile which give user a way to set
power profile through parameters minimum sclk, minimum mclk,
activity threshold, up hysteresis and down hysteresis only
when the entry power_dpm_force_performance_level is in
default value "auto". It is read and write. Example:

echo 500 800 20 0 5 > /sys/class/drm/card0/device/pp_*_power_profile

cat /sys/class/drm/card0/device/pp_*_power_profile
500 800 20 0 5

Note: first parameter is sclk in MHz, second is mclk in MHz,
third is activity threshold in percentage, fourth is up hysteresis
in ms and fifth is down hysteresis in ms.

echo set > /sys/class/drm/card0/device/pp_*_power_profile
To set power profile state if it exists.

echo reset > /sys/class/drm/card0/device/pp_*_power_profile
To restore default state and clear previous setting.

Signed-off-by: Eric Huang <JinHuiEric.Huang@amd.com>
Acked-by: Rex Zhu <Rex.Zhu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>