of: Add helper for printing an of_phandle_args structure

It is sometimes useful for debug to get the contents of an
of_phandle_args structure out into the kernel log.

Signed-off-by: Grant Likely <grant.likely@linaro.org>

diff --cc drivers/of/base.c
Simple merge

diff --cc drivers/of/irq.c
Simple merge

diff --cc include/linux/of.h
Simple merge