nfp: bpf: support BPF offload only on little endian

eBPF is host-endian specific.  Translating both BE and LE eBPF
to the NFP is feasible, but would require quite a bit of indirection.
The fact that I don't have access to any BE hosts that would fit
a 25G/40G/100G NIC is also limiting my ability to test big endian.

For now restrict the offload to little endian hosts only.
Signed-off-by: NJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: NSimon Horman <simon.horman@netronome.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/netronome/nfp/bpf/main.c

@@ -42,9 +42,11 @@
 
 static bool nfp_net_ebpf_capable(struct nfp_net *nn)
 {
+#ifdef __LITTLE_ENDIAN
 	if (nn->cap & NFP_NET_CFG_CTRL_BPF &&
 	    nn_readb(nn, NFP_NET_CFG_BPF_ABI) == NFP_NET_BPF_ABI)
 		return true;
+#endif
 	return false;
 }