alpha: PTR_ERR overwrites -EINVAL in syscall osf_mount

The initial -EINVAL value is overwritten by `retval = PTR_ERR(name)'.  If
this isn't an error pointer and typenr is not 1, 6 or 9, then this retval,
a pointer cast to a long, is returned.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Acked-by: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Matt Turner <mattst88@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>