The return code of hw_perf_event_update() is not evaluated by
its callers.  Hence, simplify the function by removing the
return code.
Reported-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NHendrik Brueckner <brueckner@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>