supports A20, A31, and A31S. Adds support for the BananaPi M2 (A31S) board. Submitted by: Emmanuel Vadot <manu@bidouilliste.com> Reviewed by: jmcneill Differential Revision: https://reviews.freebsd.org/D5580
will be needed when we bring in further support for these SoCs. Submitted by: Emmanuel Vadot <manu@bidouilliste.com> Differential Revision: https://reviews.freebsd.org/D5340