drm/amdgpu: align pp_power_profile_mode with kernel docs

The kernel doc says you need to select manual mode to
adjust this, but the code only allows you to adjust it when
manual mode is not selected.  Remove the manual mode check.

Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit bbb05f8a)
Cc: stable@vger.kernel.org