bna: fix firmware loading on big-endian machines

Firmware required by bna is stored in appropriate files as sequence
of LE32 integers. After loading by request_firmware() they need to be
byte-swapped on big-endian arches. Without this conversion the NIC
is unusable on big-endian machines.

Cc: Rasesh Mody <rasesh.mody@qlogic.com>
Signed-off-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>