nfp: bpf: pass dst register to ld_field instruction

ld_field instruction is a bit special because the encoding uses
two source registers and one of them becomes the output.  We do
need to pass the dst register to our encoding helpers though,
otherwise the "write both banks" flag will not be observed.
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/jit.c

@@ -408,7 +408,8 @@ emit_ld_field_any(struct nfp_prog *nfp_prog, enum shf_sc sc, u8 shift,
 	struct nfp_insn_re_regs reg;
 	int err;
 
-	err = swreg_to_restricted(reg_none(), dst, src, &reg, true);
+	/* Note: ld_field is special as it uses one of the src regs as dst */
+	err = swreg_to_restricted(dst, dst, src, &reg, true);
 	if (err) {
 		nfp_prog->error = err;
 		return;