powerpc: bpf: Fix the broken LD_VLAN_TAG_PRESENT test

We have to return the boolean here if the tag presents
or not, not just ANDing the TCI with the mask which results to:

[  709.412097] test_bpf: #18 LD_VLAN_TAG_PRESENT
[  709.412245] ret 4096 != 1
[  709.412332] ret 4096 != 1
[  709.412333] FAIL (2 times)

Signed-off-by: Denis Kirjanov <kda@linux-powerpc.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/powerpc/net/bpf_jit_comp.c

@@ -394,10 +394,12 @@ static int bpf_jit_build_body(struct sk_filter *fp, u32 *image,
 
 			PPC_LHZ_OFFS(r_A, r_skb, offsetof(struct sk_buff,
 							  vlan_tci));
-			if (code == (BPF_ANC | SKF_AD_VLAN_TAG))
+			if (code == (BPF_ANC | SKF_AD_VLAN_TAG)) {
 				PPC_ANDI(r_A, r_A, ~VLAN_TAG_PRESENT);
-			else
+			} else {
 				PPC_ANDI(r_A, r_A, VLAN_TAG_PRESENT);
+				PPC_SRWI(r_A, r_A, 12);
+			}
 			break;
 		case BPF_ANC | SKF_AD_QUEUE:
 			BUILD_BUG_ON(FIELD_SIZEOF(struct sk_buff,