selftests/bpf: Fix test_verifier failed test in unprivileged mode

Loading the BTF won't be permitted without privileges, hence only test
for privileged mode by setting the prog type. This makes the
test_verifier show 0 failures when unprivileged BPF is enabled.

Fixes: 41188e9e9d ("selftest/bpf: Test for use-after-free bug fix in inline_bpf_loop")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220721134245.2450-14-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

tools/testing/selftests/bpf/verifier/bpf_loop_inline.c

@@ -251,6 +251,7 @@
 	.expected_insns = { PSEUDO_CALL_INSN() },
 	.unexpected_insns = { HELPER_CALL_INSN() },
 	.result = ACCEPT,
+	.prog_type = BPF_PROG_TYPE_TRACEPOINT,
 	.func_info = { { 0, MAIN_TYPE }, { 16, CALLBACK_TYPE } },
 	.func_info_cnt = 2,
 	BTF_TYPES