[SPARC64]: %l6 trap return handling no longer necessary.

Now that we indicate the "restart system call" in the
trap type field of pt_regs->magic, we don't need to
set the %l6 boolean in all of the trap return paths.

And we therefore don't need to pass it to do_notify_resume().

Signed-off-by: David S. Miller <davem@davemloft.net>