KKASSERT panic in DAIOCTRIM from non-512-aligned user-supplied offsets

Summary

daioctl() enforces 512-byte alignment of user-supplied TRIM range via two KKASSERT() calls instead of returning EINVAL. Any caller that passes del_num not multiple of 512 triggers kernel assertion failure -> panic. KKASSERT in DragonFly expands to panic on failure. User-controlled alignment enforced by fatal assert rather than EINVAL return. Reachable directly: open /dev/daXsY (requires SYSCAP_RESTRICTEDROOT) then ioctl(fd DAIOCTRIM &args) with any non-multiple-of-512 value.