selftests/bpf: fix a typo in map in map test

Commit fbeb1603bf4e ("bpf: verifier: MOV64 don't mark dst reg unbounded")
revealed a typo in commit fb30d4b71214 ("bpf: Add tests for map-in-map"):
BPF_MOV64_REG(BPF_REG_0, 0) was used instead of
BPF_MOV64_IMM(BPF_REG_0, 0).

I've noticed the problem by running bpf kselftests.

Fixes: fb30d4b71214 ("bpf: Add tests for map-in-map")
Signed-off-by: Roman Gushchin <guro@fb.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Arthur Fabre <afabre@cloudflare.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

tools/testing/selftests/bpf/test_verifier.c

@@ -7113,7 +7113,7 @@ static struct bpf_test tests[] = {
 			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
 			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
 				     BPF_FUNC_map_lookup_elem),
-			BPF_MOV64_REG(BPF_REG_0, 0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
 			BPF_EXIT_INSN(),
 		},
 		.fixup_map_in_map = { 3 },
@@ -7136,7 +7136,7 @@ static struct bpf_test tests[] = {
 			BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, 8),
 			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
 				     BPF_FUNC_map_lookup_elem),
-			BPF_MOV64_REG(BPF_REG_0, 0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
 			BPF_EXIT_INSN(),
 		},
 		.fixup_map_in_map = { 3 },
@@ -7158,7 +7158,7 @@ static struct bpf_test tests[] = {
 			BPF_MOV64_REG(BPF_REG_1, BPF_REG_0),
 			BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0,
 				     BPF_FUNC_map_lookup_elem),
-			BPF_MOV64_REG(BPF_REG_0, 0),
+			BPF_MOV64_IMM(BPF_REG_0, 0),
 			BPF_EXIT_INSN(),
 		},
 		.fixup_map_in_map = { 3 },