pasemi_mac: Fix building as module

Commit ded19add ('pasemic_mac*: Move
the PA Semi driver') inadvertently split pasemi_mac into two separate
modules with unresolved symbols.  Change it back into a single module.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>