powerpc: ps3/device-init.c - adapt to completions using swait vs wait

To fix:

  cc1: warnings being treated as errors
  arch/powerpc/platforms/ps3/device-init.c: In function 'ps3_notification_read_write':
  arch/powerpc/platforms/ps3/device-init.c:755:2: error: passing argument 1 of 'prepare_to_wait_event' from incompatible pointer type
  arch/powerpc/platforms/ps3/device-init.c:755:2: error: passing argument 1 of 'abort_exclusive_wait' from incompatible pointer type
  arch/powerpc/platforms/ps3/device-init.c:755:2: error: passing argument 1 of 'finish_wait' from incompatible pointer type
  arch/powerpc/platforms/ps3/device-init.o] Error 1
  make[3]: *** Waiting for unfinished jobs....

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>