[PATCH] ieee80211: Move IV/ICV stripping into ieee80211_rx

This patch adds a host_strip_iv_icv flag to ieee80211 which indicates that
ieee80211_rx should strip the IV/ICV/other security features from the payload.
This saves on some memmove() calls in the driver and seems like something that
belongs in the stack as it can be used by bcm43xx, ipw2200, and zd1211rw

I will submit the ipw2200 patch separately as it needs testing.

This patch also adds some sensible variable reuse (idx vs keyidx) in
ieee80211_rx

Signed-off-by: Daniel Drake <dsd@gentoo.org>
Acked-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>