selftests/bpf: Fix a typo in test_maps

Trivial fix to a typo in the test_map_wronly test: "read" -> "write"
Signed-off-by: NAnton Protopopov <a.s.protopopov@gmail.com>
Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200527185700.14658-2-a.s.protopopov@gmail.comSigned-off-by: NAlexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/test_maps.c

@@ -1410,7 +1410,7 @@ static void test_map_wronly(void)
 	fd = bpf_create_map(BPF_MAP_TYPE_HASH, sizeof(key), sizeof(value),
 			    MAP_SIZE, map_flags | BPF_F_WRONLY);
 	if (fd < 0) {
-		printf("Failed to create map for read only test '%s'!\n",
+		printf("Failed to create map for write only test '%s'!\n",
 		       strerror(errno));
 		exit(1);
 	}