bpf: Fix warning for bpf_cpumask in verifier

Compiling with CONFIG_BPF_SYSCALL & !CONFIG_BPF_JIT throws the below
warning:

  "WARN: resolve_btfids: unresolved symbol bpf_cpumask"

Fix it by adding the appropriate #ifdef.

Signed-off-by: Hari Bathini <[email protected]>
Signed-off-by: Andrii Nakryiko <[email protected]>
Acked-by: Jiri Olsa <[email protected]>
Acked-by: Stanislav Fomichev <[email protected]>
Acked-by: David Vernet <[email protected]>
Link: https://lore.kernel.org/bpf/[email protected]

Author: hbathini

kernel/bpf/verifier.c

@@ -5227,7 +5227,9 @@ BTF_ID(struct, prog_test_ref_kfunc)
 #ifdef CONFIG_CGROUPS
 BTF_ID(struct, cgroup)
 #endif
+#ifdef CONFIG_BPF_JIT
 BTF_ID(struct, bpf_cpumask)
+#endif
 BTF_ID(struct, task_struct)
 BTF_SET_END(rcu_protected_types)