samples: bpf: Fix conflicting types in fds_example

Fix the following samples/bpf build error appeared after the
introduction of bpf_map_create() in libbpf:

  CC  samples/bpf/fds_example.o
samples/bpf/fds_example.c:49:12: error: static declaration of 'bpf_map_create' follows non-static declaration
static int bpf_map_create(void)
           ^
samples/bpf/libbpf/include/bpf/bpf.h:55:16: note: previous declaration is here
LIBBPF_API int bpf_map_create(enum bpf_map_type map_type,
               ^
samples/bpf/fds_example.c:82:23: error: too few arguments to function call, expected 6, have 0
                fd = bpf_map_create();
                     ~~~~~~~~~~~~~~ ^
samples/bpf/libbpf/include/bpf/bpf.h:55:16: note: 'bpf_map_create' declared here
LIBBPF_API int bpf_map_create(enum bpf_map_type map_type,
               ^
2 errors generated.

fds_example by accident has a static function with the same name.
It's not worth it to separate a single call into its own function,
so just embed it.

Fixes: 992c4225 ("libbpf: Unify low-level map creation APIs w/ new bpf_map_create()")
Signed-off-by: Alexander Lobakin <alexandr.lobakin@intel.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20211201164931.47357-1-alexandr.lobakin@intel.com