sparc64: tracehook syscall

This changes sparc64 syscall tracing to use the new tracehook.h entry
points.

[ Add assembly changes to force an immediate -ENOSYS return from
  the system call when syscall_trace() returns non-zero at syscall
  entry.  -DaveM ]

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>