libbpf: Use __u32 fields in bpf_map_create_opts

Corresponding Linux UAPI struct uses __u32, not int, so keep it
consistent.

Fixes: 992c4225 ("libbpf: Unify low-level map creation APIs w/ new bpf_map_create()")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211201232824.3166325-2-andrii@kernel.org

tools/lib/bpf/bpf.h

@@ -43,12 +43,12 @@ struct bpf_map_create_opts {
 	__u32 btf_value_type_id;
 	__u32 btf_vmlinux_value_type_id;
 
-	int inner_map_fd;
-	int map_flags;
+	__u32 inner_map_fd;
+	__u32 map_flags;
 	__u64 map_extra;
 
-	int numa_node;
-	int map_ifindex;
+	__u32 numa_node;
+	__u32 map_ifindex;
 };
 #define bpf_map_create_opts__last_field map_ifindex