samples: bpf: rename libbpf.h to bpf_insn.h

The libbpf.h file in samples is clashing with libbpf's header.
Since it only includes a subset of filter.h instruction helpers
rename it to bpf_insn.h.  Drop the unnecessary include of bpf/bpf.h.

Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

samples/bpf/fds_example.c

@@ -12,8 +12,10 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 
+#include <bpf/bpf.h>
+
+#include "bpf_insn.h"
 #include "bpf_load.h"
-#include "libbpf.h"
 #include "sock_example.h"
 
 #define BPF_F_PIN	(1 << 0)