mac80211: remove wep dependency

The current mac80211 code assumes that WEP is always available.  If WEP
fails to initialize, ieee80211_register_hw will always fail.

In some cases (e.g. FIPS certification), the cryptography used by WEP is
unavailable.  However, in such cases there is no good reason why CCMP
encryption (or even no link level encryption) cannot be used.  So, this
patch removes mac80211's assumption that WEP (and TKIP) will always be
available for use.

Signed-off-by: John W. Linville <linville@tuxdriver.com>