Reset bss_index on AP start

bss_index must be set to 0xFF every time AP mode
is started.

Signed-off-by: Eugene Krasnikov <k.eugene.e@gmail.com>
In AP mode notify upper layers whet sta was lost

HW will notify driver through delete_sta_context_ind that sta was lost.
Report low ack to wpa_supplicant so it can take an action on that.
wpa_supplicant will disconnect sta if in conf file flag is set like
this disassoc_low_ack=1.

Signed-off-by: Eugene Krasnikov <k.eugene.e@gmail.com>
Fix checkpatch warnings

Run checkpatch on the following files:
main.c
smd.c
txrx.c

Signed-off-by: Eugene Krasnikov <k.eugene.e@gmail.com>
Fix checkpatch warnings in DXE and HAL

All errors and warnings after running checkpatch were fixed
in following files:
dxe.c
dxe.h
hal.h

Signed-off-by: Eugene Krasnikov <k.eugene.e@gmail.com>