Don't attempt to do DHCP on certain interfaces, similar to what's done for
ipv6_autoconfif() in r212577.

MFC after:	1 week
Add identification for Cortex-A15 (R0) cores.

Submitted by:	Ruslan Bukin <br@bsdpad.com>
Bump max number of IRQs for Cortex-Ax family to cover Exynos5 requirement.

Submitted by:	Ruslan Bukin <br@bsdpad.com>