syscall.master: fix aio_suspend signature

[brooks]

Summary

It takes a const struct iovec *iovp.

[kib]

Ok, but this change by itself does not change much. Do we want to consticize locals in sys_aio_suspend() and args for kern_aio_suspend()?

[brooks]

In D44378#1012165, @kib wrote:

Ok, but this change by itself does not change much. Do we want to consticize locals in sys_aio_suspend() and args for kern_aio_suspend()?

This aligns the declaration with aio_suspend(9). It presumably also has the side effect of preventing passing uap->aiocbp argument to copyout without a cast, but my goal here is just to align with the syscall declaration.