selftests: bpf: Remove unused bpf_map_def_legacy struct

samples/bpf no longer use bpf_map_def_legacy and instead use the
libbpf's bpf_map_def or new BTF-defined MAP format. This commit removes
unused bpf_map_def_legacy struct from selftests/bpf/bpf_legacy.h.

Signed-off-by: Daniel T. Lee <[e-mail]>
Signed-off-by: Daniel Borkmann <[e-mail]>
Acked-by: Andrii Nakryiko <[e-mail]>
Link: https://lore.kernel.org/bpf/[e-mail]

tools/testing/selftests/bpf/bpf_legacy.h

···
 #ifndef __BPF_LEGACY__
 #define __BPF_LEGACY__
 
-/*
- * legacy bpf_map_def with extra fields supported only by bpf_load(), do not
- * use outside of samples/bpf
- */
-struct bpf_map_def_legacy {
-	unsigned int type;
-	unsigned int key_size;
-	unsigned int value_size;
-	unsigned int max_entries;
-	unsigned int map_flags;
-	unsigned int inner_map_idx;
-	unsigned int numa_node;
-};
-
 #define BPF_ANNOTATE_KV_PAIR(name, type_key, type_val)		\
 	struct ____btf_map_##name {				\
 		type_key key;					\