of/address: Don't throw errors on absent ranges properties

The core always tries to translate any "reg" property to construct the platform
device names. This results in a pile of "OF: no ranges; cannot translate" errors
in dmesg whenever we expose things like i2c devices that cannot directly translate
to the MMIO space.

Turn this into a pr_debug instead

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Grant Likely <grant.likely@linaro.org>