Disable debugging by default.
- Add display-related and clk devices to the tree
- Prevent resources intersection with EHCI driver
Add driver for Display Controller.
Add support for Samsung Chromebook (ARM Cortex A15 machine).
share/man/man7/tests.7
	Added a section on test suite configuration, and cleaned up up
	grammar errors and awkward prose.  The config variables were
	discussed on freebsd-testing.

Discussed with: Garrett Cooper, jmmv
MFC after:	2 weeks
Sponsored by:	Spectra Logic Corporation