perf: arm64: Record the user-mode PC in the call chain.

With this change, we no longer lose the innermost entry in the user-mode
part of the call chain. See also the x86 port, which includes the ip,
and the corresponding change in arch/arm.

Signed-off-by: Jed Davis <[e-mail]>
Acked-by: Ingo Molnar <[e-mail]>
Acked-by: Will Deacon <[e-mail]>
Cc: [e-mail]
Signed-off-by: Catalin Marinas <[e-mail]>

arch/arm64/kernel/perf_event.c

···
 		return;
 	}
 
+	perf_callchain_store(entry, regs->pc);
 	tail = (struct frame_tail __user *)regs->regs[29];
 
 	while (entry->nr < PERF_MAX_STACK_DEPTH &&