seccomp/mips: change syscall_trace_enter() to use secure_computing()

seccomp/mips: change syscall_trace_enter() to use secure_computing()

arch/mips/Kconfig selects HAVE_ARCH_SECCOMP_FILTER so syscall_trace_enter()
can just use __secure_computing(NULL) and rely on populate_seccomp_data(sd)
and "sd == NULL" checks in __secure_computing(sd) paths.

With the change above syscall_trace_enter() can just use secure_computing()
and avoid #ifdef + test_thread_flag(TIF_SECCOMP). CONFIG_GENERIC_ENTRY is
not defined, so test_syscall_work(SECCOMP) will check TIF_SECCOMP.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Reviewed-by: Kees Cook <kees@kernel.org>
Link: https://lore.kernel.org/r/20250128150300.GA15318@redhat.com
Signed-off-by: Kees Cook <kees@kernel.org>