bpf/tests: Fix copy-and-paste error in double word test

This test now operates on DW as stated instead of W, which was
already covered by another test.

Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210721104058.3755254-1-johan.almbladh@anyfinetworks.com

lib/test_bpf.c

@@ -4286,8 +4286,8 @@ static struct bpf_test tests[] = {
 		.u.insns_int = {
 			BPF_LD_IMM64(R0, 0),
 			BPF_LD_IMM64(R1, 0xffffffffffffffffLL),
-			BPF_STX_MEM(BPF_W, R10, R1, -40),
-			BPF_LDX_MEM(BPF_W, R0, R10, -40),
+			BPF_STX_MEM(BPF_DW, R10, R1, -40),
+			BPF_LDX_MEM(BPF_DW, R0, R10, -40),
 			BPF_EXIT_INSN(),
 		},
 		INTERNAL,