device: rename DECLARE_DEVICE_INIT_CONFIG()

Rename it to DEVICE_INIT_CONFIG_DEFINE(), because (a) it was not fitting
in any namespace and (b) it is not used to declare, but rather define a
object.

Change-Id: I1da5822f06b85a9fb024b5b184afd0ccc01012ec
Signed-off-by: Benjamin Walsh <benjamin.walsh@windriver.com>