wireless: Fix rate mask for scan request

The scan request received from cfg80211_connect do not
have proper rate mast. So the probe request sent on each
channel do not have proper the supported rates ie.

Cc: stable@kernel.org
Reviewed-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Rajkumar Manoharan <rmanohar@qca.qualcomm.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>