net: wireless: bcmdhd abort ongoing-scan for disconnection

sometimes we cannot get WLC_E_DEAUTH due to ongoing-scan
We need to abort ongoing-scan for disconnection

Bug: 18634452
Signed-off-by: Ecco park <eccopark@broadcom.com>
Change-Id: I2c416738418ce4915dcfbaa57bb3d701269eecc8