of: Transactional DT support.

of: Transactional DT support.

Introducing DT transactional support.

A DT transaction is a method which allows one to apply changes
in the live tree, in such a way that either the full set of changes
take effect, or the state of the tree can be rolled-back to the
state it was before it was attempted. An applied transaction
can be rolled-back at any time.

Documentation is in
	Documentation/devicetree/changesets.txt

Signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
[glikely: Removed device notifiers and reworked to be more consistent]
Signed-off-by: Grant Likely <grant.likely@linaro.org>
(cherry picked from commit 201c910bd6898d81d4ac6685d0f421b7e10f3c5d)
Signed-off-by: Mark Brown <broonie@kernel.org>
Conflicts:
	drivers/of/selftest.c
	drivers/of/testcase-data/testcases.dtsi
	include/linux/of.h