nvme(4): Increase HMB alignment.

The NVME controller in Crucial P310 disk does not accept 16-byte aligned
host memory buffer on Codasip Prime platform, but works fine on PAGE_SIZE
aligned memory.

Instead of adding a quirk, just increase alignment for everyone.

Reviewed by: jhb
Discussed with: imp
Sponsored by: CHERI Research Centre
Differential Revision: https://reviews.freebsd.org/D53296