au1550 ac97 driver works fine on au1200 too.

Comments at the top of file state this code is GPL, so lets
mark it as GPL too.
Signed-off-by: Domen Puncer <domen.puncer@ultra.si>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>