brcmfmac: fix big endian bug in i-scan.

ssid len is 32 bit and needs endian conversion for big endian systems.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Hante Meuleman <meuleman@broadcom.com>
Signed-off-by: Arend van Spriel <arend@broadcom.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>