ssb: Handle alternate SSPROM location

In kernel Bugzilla #15825 (2 users), in a wireless mailing list thread
(http://lists.infradead.org/pipermail/b43-dev/2010-May/000124.html), and on a
netbook owned by John Linville
(http://marc.info/?l=linux-wireless&m=127230751408818&w=4), there are reports
of ssb failing to detect an SPROM at the normal location. After studying the
MMIO trace dump for the Broadcom wl driver, it was determined that the affected
boxes had a relocated SPROM.

This patch fixes all systems that have reported this problem.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Stable <stable@kernel.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>