selftests/bpf: Fix bind{4,6} tcp/socket header type conflict

There is a potential for us to hit a type conflict when including
netinet/tcp.h with sys/socket.h, we can remove these as they are not
actually needed.

Fixes errors like the below when compiling with gcc BPF backend:

  In file included from /usr/include/netinet/tcp.h:91,
                   from progs/bind4_prog.c:10:
  /home/buildroot/opt/cross/lib/gcc/bpf/13.0.0/include/stdint.h:34:23: error: conflicting types for 'int8_t'; have 'char'
     34 | typedef __INT8_TYPE__ int8_t;
        |                       ^~~~~~
  In file included from /usr/include/x86_64-linux-gnu/sys/types.h:155,
                   from /usr/include/x86_64-linux-gnu/bits/socket.h:29,
                   from /usr/include/x86_64-linux-gnu/sys/socket.h:33,
                   from progs/bind4_prog.c:9:
  /usr/include/x86_64-linux-gnu/bits/stdint-intn.h:24:18: note: previous declaration of 'int8_t' with type 'int8_t' {aka 'signed char'}
     24 | typedef __int8_t int8_t;
        |                  ^~~~~~
  /home/buildroot/opt/cross/lib/gcc/bpf/13.0.0/include/stdint.h:43:24: error: conflicting types for 'int64_t'; have 'long int'
     43 | typedef __INT64_TYPE__ int64_t;
        |                        ^~~~~~~
  /usr/include/x86_64-linux-gnu/bits/stdint-intn.h:27:19: note: previous declaration of 'int64_t' with type 'int64_t' {aka 'long long int'}
     27 | typedef __int64_t int64_t;
        |                   ^~~~~~~
  make: *** [Makefile:537: /home/buildroot/bpf-next/tools/testing/selftests/bpf/bpf_gcc/bind4_prog.o] Error 1
Signed-off-by: James Hilliard <james.hilliard1@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220826052925.980431-1-james.hilliard1@gmail.com

tools/testing/selftests/bpf/progs/bind4_prog.c

@@ -6,8 +6,6 @@
 #include <linux/bpf.h>
 #include <linux/in.h>
 #include <linux/in6.h>
-#include <sys/socket.h>
-#include <netinet/tcp.h>
 #include <linux/if.h>
 #include <errno.h>
 

tools/testing/selftests/bpf/progs/bind6_prog.c

@@ -6,8 +6,6 @@
 #include <linux/bpf.h>
 #include <linux/in.h>
 #include <linux/in6.h>
-#include <sys/socket.h>
-#include <netinet/tcp.h>
 #include <linux/if.h>
 #include <errno.h>