Fix calls to pthread_setschedparam.

When the scheduling priority is set to SCHED_NORMAL, you may not
specify a non-zero priority. The current implementation does
exactly that resulting in the call failing and returning EINVAL.
This change ensures that a priority of 0 is set when the desired
scheduler policy is set to SCHED_NORMAL.

http://b/12304174

Change-Id: I945cae175b7bdd29dd8fc130ff6396b88ec33fcb
Revert "bluetooth: Do not sleep when you have already overslept your tick"

 * Obsolete, and is causing more harm than good. Reverting this patch
   solves the sporadic AD2P timer jank.

This reverts commit a73420d385097af6212f94da2d7020811a8bb580.

Change-Id: I4800e975a2183e8202c002e06facf3b2133158ea