arm64: locks: introduce ticket-based spinlock implementation

This patch introduces a ticket lock implementation for arm64, along the
same lines as the implementation for arch/arm/.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --cc arch/arm64/include/asm/spinlock.h
Simple merge

diff --cc arch/arm64/include/asm/spinlock_types.h
Simple merge