bhyve: add table dump functions for basl

Developing an ACPI table compiler isn't quite easy. It's helpful if you
can take a look at the ACPI tables created by the compiler.

The dump functions can either dump a ACPI table which was copied into
guest memory or a ACPI table provided for qemu's ACPI table loader.

Reviewed by: jhb, markj
Approved by: manu (mentor)
MFC after: 2 weeks
Sponsored by: Beckhoff Automation GmbH & Co. KG
Differential Revision: https://reviews.freebsd.org/D36985

(cherry picked from commit ac3c2b3e38fb03b0d0e26ffa0527735575984ba2)