rndis_wlan: increase scan timer delay

Increase scan delay from 1 sec to 6 sec. Spec says that scan by
OID_802_11_BSSID_LIST_SCAN completes in 6 seconds.
Before rfkill patch too short delay was not problem as device was
always active (radio on) and performing background scanning.

Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>