ARM: mcpm, perf/arm-cci: export mcpm_is_available

Now that the ARM CCI PMU driver can be built as a loadable module,
we get a link failure when MCPM is enabled:

ERROR: "mcpm_is_available" [drivers/perf/arm-cci.ko] undefined!

The simplest fix is to export that helper function.

Fixes: 8b0c93c2 ("perf/arm-cci: Allow building as a module")
Acked-by: Nicolas Pitre <nico@linaro.org>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm/common/mcpm_entry.c

@@ -9,6 +9,7 @@
  * published by the Free Software Foundation.
  */
 
+#include <linux/export.h>
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/irqflags.h>
@@ -174,6 +175,7 @@ bool mcpm_is_available(void)
 {
 	return (platform_ops) ? true : false;
 }
+EXPORT_SYMBOL_GPL(mcpm_is_available);
 
 /*
  * We can't use regular spinlocks. In the switcher case, it is possible