Use DEVICE memory instead of UNCACHEABLE on aarch64 in ioremap() in the LinuxKPI.
This fixes system hangs on reading device registers on aarch64.

Tested with: Marvell MACCHIATObin (Armada8k) + mlx4en, amdgpu
Submitted by: Greg V <greg@unrelenting.technology>
Differential Revision: https://reviews.freebsd.org/D20789
MFC after: 1 week
Sponsored by: Mellanox Technologies