iwlwifi regression in 20111205 merge

  It looks like the regression was introduced between 20111202 and
20111205 (linux-next tree). Symptoms: connection to AP seem to be
established, but no data goes though it in any way. Tested on intel
5300.
  Peek at the changes have shown that it looks like at least part of
the code wasn't merged properly. It was originally committed into
iwl_agn.c but code in question was moved to iwl-mac80211.c.
  This patch puts code in place and my card works again.

Signed-off-by: Nikolay Martynov <mar.kolya@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>