perf/x86: Clean up register_nmi_handler() usage

A function name represents the pointer to it - no need to take the
address of it. (Fixing this helps us introduce some macro magic
around register_nmi_handler() in the future.)

Cc: Robert Richter <robert.richter@amd.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/perf_event_amd_ibs.c

@@ -469,7 +469,7 @@ static __init int perf_event_ibs_init(void)
 
 	perf_ibs_pmu_init(&perf_ibs_fetch, "ibs_fetch");
 	perf_ibs_pmu_init(&perf_ibs_op, "ibs_op");
-	register_nmi_handler(NMI_LOCAL, &perf_ibs_nmi_handler, 0, "perf_ibs");
+	register_nmi_handler(NMI_LOCAL, perf_ibs_nmi_handler, 0, "perf_ibs");
 	printk(KERN_INFO "perf: AMD IBS detected (0x%08x)\n", ibs_caps);
 
 	return 0;