libertas: Add support for Marvell Libertas CF8305

libertas: Add support for Marvell Libertas CF8305

The CF8305 is a very old silicon running firmware version 3.0 . This card also
needs some special treatment as it's so old it can't do unaligned register
access. But since that happens only at one place, there were no changes made to
the register access functions, but instead that particular place was fixed.
Also, this card uses only one-stage firmware which is loaded the same way as
helper firmware. The second-stage firmware isn't loaded on this card and doesn't
therefore have to be supplied.

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>