of: Modify of_device_get_modalias to be passed struct device

Now that the of_node pointer is part of struct device,
of_device_get_modalias could be used on any struct device
that has the device node pointer set.  This patch changes
of_device_get_modalias to accept a struct device instead
of a struct of_device.

Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
CC: Michal Simek <monstr@monstr.eu>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Wolfram Sang <w.sang@pengutronix.de>
CC: Stephen Rothwell <sfr@canb.auug.org.au>
CC: microblaze-uclinux@itee.uq.edu.au
CC: linuxppc-dev@ozlabs.org