sched/topology, arch/arm64: Rebuild the sched_domain hierarchy when the CPU capacity changes

Asymmetric CPU capacity can not necessarily be determined accurately at
the time the initial sched_domain hierarchy is built during boot. It is
therefore necessary to be able to force a full rebuild of the hierarchy
later triggered by the arch_topology driver. A full rebuild requires the
arch-code to implement arch_update_cpu_topology() which isn't yet
implemented for arm64. This patch points the arm64 implementation to
arch_topology driver to ensure that full hierarchy rebuild happens when
needed.

Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will.deacon@arm.com>
Cc: dietmar.eggemann@arm.com
Cc: valentin.schneider@arm.com
Cc: vincent.guittot@linaro.org
Link: http://lkml.kernel.org/r/1532093554-30504-4-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/arm64/include/asm/topology.h

@@ -45,6 +45,9 @@ int pcibus_to_node(struct pci_bus *bus);
 /* Replace task scheduler's default cpu-invariant accounting */
 #define arch_scale_cpu_capacity topology_get_cpu_scale
 
+/* Enable topology flag updates */
+#define arch_update_cpu_topology topology_update_cpu_topology
+
 #include <asm-generic/topology.h>
 
 #endif /* _ASM_ARM_TOPOLOGY_H */