ARM: perf: fix prototype of release_pmu

Commit  f12482c9 ("ARM: 6974/1: pmu: refactor reservation") changed the
prototype of release_pmu, but missed the stub for when
CONFIG_CPU_HAS_PMU is not selected by the platform.

This patch changes the prototype of the stub, preventing possible build
failures when CONFIG_CPU_HAS_PMU is not selected.
Signed-off-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

arch/arm/include/asm/pmu.h

@@ -75,7 +75,7 @@ reserve_pmu(enum arm_pmu_type device)
 }
 
 static inline int
-release_pmu(struct platform_device *pdev)
+release_pmu(enum arm_pmu_type device)
 {
 	return -ENODEV;
 }