[SPARC]: Stop-A printk cleanup

This patch is incredibly trivial, but it does resolve some of the user
confusion as to what "L1-A" actually is.

Clarify printk message to refer to Stop-A (L1-A).

Gentoo has a virtually identical patch in their kernel sources.

Signed-off-by: Tom 'spot' Callaway <tcallawa@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>