m68k: assign syscall number for seccomp

Most architectures have assigned a numbers for the seccomp syscall
even when they do not implement it.

m68k is an exception here, so for consistency lets add the number.
Unless CONFIG_SECCOMP is implemented, the system call just
returns -ENOSYS.
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/m68k/kernel/syscalls/syscall.tbl

@@ -387,3 +387,4 @@
 377	common	preadv2				sys_preadv2
 378	common	pwritev2			sys_pwritev2
 379	common	statx				sys_statx
+380	common	seccomp				sys_seccomp