nfp: bpf: calculate code store ECC

In the initial PoC firmware I simply disabled ECC on the instruction
store.  Do the ECC calculation for generated instructions in the driver.

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>