[MAC80211]: Set low initial rate in rc80211_simple

The initial rate for STA's using rc80211_simple is set to the last
rate in the rate table. For situations for which the signal is weak,
the rate may be too high for authentication and association. Although
the rc80211_simple module will adjust the speed, the response may not
be fast enough for a successful connection. This modification sets the
initial rate to the lowest supported value.

Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net>
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>