x86/events, drivers/iommu/amd: Introduce amd_iommu_get_num_iommus()

Introduce amd_iommu_get_num_iommus(), which returns the value of
amd_iommus_present. The function is used to replace direct access to the
variable, which is now declared as static.

This function will also be used by AMD IOMMU perf driver.

Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Jörg Rödel <joro@8bytes.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vince Weaver <vincent.weaver@maine.edu>
Cc: iommu@lists.linux-foundation.org
Link: http://lkml.kernel.org/r/1487926102-13073-6-git-send-email-Suravee.Suthikulpanit@amd.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

drivers/iommu/amd_iommu_proto.h

@@ -21,6 +21,7 @@
 
 #include "amd_iommu_types.h"
 
+extern int amd_iommu_get_num_iommus(void);
 extern int amd_iommu_init_dma_ops(void);
 extern int amd_iommu_init_passthrough(void);
 extern irqreturn_t amd_iommu_int_thread(int irq, void *data);