Suppress some of the Power Management debug log messages

Suppress some of the Power Management debug log messages that
are printed by default. Some of those messages can be very chatty
if the pairing devices cannot agree on the sniff interval.

For performance reasons, we cannot relax the Nexus Player's
sniff interval, hence those debug log messages shouldn't be
printed by default.

Bug: 22040710
Change-Id: I9a01c7a547b3c592192547e3e6000135ee97d6bf