ARM64: smp: Fix function prototypes

The following prototypes lost a void during a merge:

arch/arm64/kernel/smp.c:833:13: error: function declaration isn't a prototype
[-Werror=strict-prototypes]
 static void local_cpu_stop()
             ^~~~~~~~~~~~~~
arch/arm64/kernel/smp.c:861:6: error: function declaration isn't a prototype
[-Werror=strict-prototypes]
 void panic_smp_self_stop()
      ^~~~~~~~~~~~~~~~~~~
Fixes: <6784375d> (Merge remote-tracking branch
'remotes/origin/tmp-1a9d9156' into msm-lahaina).

Change-Id: Ic0dedbadf87a76cf632e2a2f51c00d275e4b1af1
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Raghavendra Rao Ananta <rananta@codeaurora.org>