net: wireless: bcm4329: Fix GCC 4.6 warning

This module has -Werror turned on, so this was causing the build to
break on GCC 4.6:

drivers/net/wireless/bcm4329/wl_iw.c: In function 'wl_iw_set_pmksa':
drivers/net/wireless/bcm4329/wl_iw.c:5149:5: error: array subscript is above array bounds [-Werror=array-bounds]
drivers/net/wireless/bcm4329/wl_iw.c:5152:5: error: array subscript is above array bounds [-Werror=array-bounds]

It's a partial 'backport' of a change made to the bcmdhd driver:

commit 09a8dc7361d0e603d9935ec7f736fabaa2e6dc7a
net: wireless: bcmdhd: Combined P2P fix

Change-Id: Ie62ad82f884c213553772ac91eaf85e17a807503
Signed-off-by: Dan Willemsen <dwillemsen@nvidia.com>
Reviewed-on: http://git-master/r/88694
GVS: Gerrit_Virtual_Submit
Reviewed-by: Stephen Warren <swarren@nvidia.com>