bpftool: Do not check return value from libbpf_set_strict_mode()

The function always returns 0, so we don't need to check whether the
return value is 0 or not.

This change was first introduced in commit a777e18f ("bpftool: Use
libbpf 1.0 API mode instead of RLIMIT_MEMLOCK"), but later reverted to
restore the unconditional rlimit bump in bpftool. Let's re-add it.
Co-developed-by: Yafang Shao <laoar.shao@gmail.com>
Signed-off-by: Quentin Monnet <quentin@isovalent.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20220610112648.29695-3-quentin@isovalent.com

tools/bpf/bpftool/main.c

@@ -507,9 +507,7 @@ int main(int argc, char **argv)
 		 * It will still be rejected if users use LIBBPF_STRICT_ALL
 		 * mode for loading generated skeleton.
 		 */
-		ret = libbpf_set_strict_mode(LIBBPF_STRICT_ALL & ~LIBBPF_STRICT_MAP_DEFINITIONS);
-		if (ret)
-			p_err("failed to enable libbpf strict mode: %d", ret);
+		libbpf_set_strict_mode(LIBBPF_STRICT_ALL & ~LIBBPF_STRICT_MAP_DEFINITIONS);
 	}
 
 	argc -= optind;