powerpc/idle: Set 'RL' field in PSSCR on POWER9HEADmain

The POWER9 does not do automatic state transitions when idling, so the
'MTL' field (Maximum Transition Level) is ignored.  Thus, setting '0'
for the 'RL' field (Requested Level) as was done means it
doesn't transition to any power saving level.  To fix this, set both the
'MTL' and the 'RL' fields to the same level.

On a Talos II at idle this drops the reported temperatures by ~10-15%.

MFC after:	3 days

0 files changed, 0 insertions, 0 deletions