libbpf: Fix trivial typo

Fix typo in comment from 'bpf_skeleton_map' to 'bpf_map_skeleton'
and from 'bpf_skeleton_prog' to 'bpf_prog_skeleton'.
Signed-off-by: Nhuangxuesen <huangxuesen@kuaishou.com>
Signed-off-by: NAndrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/1638755236-3851199-1-git-send-email-hxseverything@gmail.com

tools/lib/bpf/libbpf.h

@@ -1038,11 +1038,11 @@ struct bpf_object_skeleton {
 	struct bpf_object **obj;
 
 	int map_cnt;
-	int map_skel_sz; /* sizeof(struct bpf_skeleton_map) */
+	int map_skel_sz; /* sizeof(struct bpf_map_skeleton) */
 	struct bpf_map_skeleton *maps;
 
 	int prog_cnt;
-	int prog_skel_sz; /* sizeof(struct bpf_skeleton_prog) */
+	int prog_skel_sz; /* sizeof(struct bpf_prog_skeleton) */
 	struct bpf_prog_skeleton *progs;
 };