ssb-pcmcia: Fix parsing of invariants tuples

This fixes parsing of the device invariants (MAC address)
for PCMCIA SSB devices.

ssb_pcmcia_do_get_invariants expects an iv pointer as data
argument.

Tested-by: dylan cristiani <d.cristiani@idem-tech.it>
Signed-off-by: Michael Buesch <mb@bu3sch.de>
Cc: stable@kernel.org
Signed-off-by: John W. Linville <linville@tuxdriver.com>