ia64: assign syscall numbers for perf and seccomp

Most architectures have assigned numbers for both seccomp and
perf_event_open, even when they do not implement either.

ia64 is an exception here, so for consistency lets add numbers for both
of them. Unless CONFIG_PERF_EVENTS and CONFIG_SECCOMP are implemented,
the system calls just return -ENOSYS.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>