perf_counter: x86: proper error propagation for the x86 hw_perf_counter_init()

Now that Paul cleaned up the error propagation paths, pass down the
x86 error as well.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Paul Mackerras <paulus@samba.org>
Orig-LKML-Reference: <20090330171023.792822360@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>