alpha: convert perf_event to use local_t

Updates the Alpha perf_event code to match the changes
recently made to the core perf_event code in commit
e78505958cf123048fb48cb56b79cebb8edd15fb.

Signed-off-by: Michael Cree <mcree@orcon.net.nz>
Signed-off-by: Matt Turner <mattst88@gmail.com>
1 file changed