drm/radeon: adjust TN dpm parameters for stability (v2)

Adjust some of the TN dpm settings for stability.  Enabling
these features causes hangs and other stability problems
on certain boards.

v2: leave uvd dpm enabled

Bug:
https://bugzilla.kernel.org/show_bug.cgi?id=63101



Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org