coresight: change ETM locking scheme from mutex to spinlock

Switch to using spinlocks instead of mutexes to make apis
callable from atomic context.

Change-Id: I6c249b66c7f9db3d6028f1ab92bacfbcf43b150e
Signed-off-by: Pratik Patel <pratikp@codeaurora.org>
1 file changed