MIPS: bpf: Fix a typo in build_one_insn()

Fix a typo in build_one_insn().

Fixes: b6bd53f9c4 ("MIPS: Add missing file for eBPF JIT.")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Cc: <stable@vger.kernel.org> # 4.13+
Patchwork: https://patchwork.linux-mips.org/patch/17491/
Signed-off-by: James Hogan <jhogan@kernel.org>

arch/mips/net/ebpf_jit.c

@@ -1513,7 +1513,7 @@ ld_skb_common:
 		}
 		src = ebpf_to_mips_reg(ctx, insn, src_reg_no_fp);
 		if (src < 0)
-			return dst;
+			return src;
 		if (BPF_MODE(insn->code) == BPF_XADD) {
 			switch (BPF_SIZE(insn->code)) {
 			case BPF_W: