arm: fixup NR_syscalls to accommodate the new seccomp syscall

This belongs in
  commit: 83f1ccba87b06575966b65352db565c363af7bcf
  https://android-review.googlesource.com/#/c/104520

Change-Id: Id5037cbebac9b86c863da79c3b8729e627e65f8e
Signed-off-by: JP Abgrall <jpa@google.com>