bpf: Fix renaming task_getsecid_subj->current_getsecid_subj.

The commit 6326948f missed renaming of task->current LSM hook in BTF_ID.
Fix it to silence build warning:
WARN: resolve_btfids: unresolved symbol bpf_lsm_task_getsecid_subj

Fixes: 6326948f ("lsm: security_task_getsecid_subj() -> security_current_getsecid_subj()")
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

kernel/bpf/bpf_lsm.c

@@ -207,7 +207,7 @@ BTF_ID(func, bpf_lsm_socket_socketpair)
 
 BTF_ID(func, bpf_lsm_syslog)
 BTF_ID(func, bpf_lsm_task_alloc)
-BTF_ID(func, bpf_lsm_task_getsecid_subj)
+BTF_ID(func, bpf_lsm_current_getsecid_subj)
 BTF_ID(func, bpf_lsm_task_getsecid_obj)
 BTF_ID(func, bpf_lsm_task_prctl)
 BTF_ID(func, bpf_lsm_task_setscheduler)