iwmc3200wifi: remove setting WEP keys before setting essid support

The recent cfg80211 "rework key operation" patch from Johannes Berg
makes sure keys are set only after the connection has been
established. So we can remove the setting WEP keys before essid
support from the driver.

Signed-off-by: Zhu Yi <yi.zhu@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>