brcmfmac: add length checks in scheduled scan result handler

commit 4835f37e upstream.

Assure the event data buffer is long enough to hold the array
of netinfo items and that SSID length does not exceed the maximum
of 32 characters as per 802.11 spec.

Reviewed-by: Hante Meuleman <hante.meuleman@broadcom.com>
Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts@broadcom.com>
Reviewed-by: Franky Lin <franky.lin@broadcom.com>
Signed-off-by: Arend van Spriel <arend.vanspriel@broadcom.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
[bwh: Backported to 3.16:
 - Move the assignment to "data" along with the assignment to "netinfo_start"
   that depends on it
 - Adjust filename, context, indentation]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>