Add ACPI entries for Synopsys Designware UARTs used on ARM platforms

This fixes (userspace) console on the Marvell MACCHIATObin in ACPI mode with
latest TianoCore EDK2 firmware.

Submitted by: Greg V <greg@unrelenting.technology>
Reviewed by: mw, bcran
Differential Revision: https://reviews.freebsd.org/D20765