perf/x86/amd: Do not print an error when the device is not present

As Linus said its not an error to not have an AMD IOMMU; esp.
when you're not even running on an AMD platform.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Link: http://lkml.kernel.org/r/20130703075542.GF23916@twins.programming.kicks-ass.netSigned-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/kernel/cpu/perf_event_amd_iommu.c

@@ -491,10 +491,8 @@ static struct perf_amd_iommu __perf_iommu = {
 static __init int amd_iommu_pc_init(void)
 {
 	/* Make sure the IOMMU PC resource is available */
-	if (!amd_iommu_pc_supported()) {
-		pr_err("perf: amd_iommu PMU not installed. No support!\n");
+	if (!amd_iommu_pc_supported())
 		return -ENODEV;
-	}
 
 	_init_perf_amd_iommu(&__perf_iommu, "amd_iommu");