nfp: bpf: byte swap the instructions

Device expects the instructions in little endian.  Make sure we
byte swap on big endian hosts.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>