arm64: Fix the arm64_personality() syscall wrapper redirection

Following commit 4378a7d4 ("arm64: implement syscall wrappers"), the
syscall function names gained the '__arm64_' prefix. Ensure that we
have the correct #define for redirecting a default syscall through a
wrapper.

Fixes: 4378a7d4 ("arm64: implement syscall wrappers")
Cc: <stable@vger.kernel.org> # 4.19.x-
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>