[POWERPC] Prepare to remove of_platform_driver name

The name field of of_platform_driver is just copied into the included
device_driver.  By not overriding an already initialised device_driver
name, we can convert the drivers over time to stop using the
of_platform_driver name.

Also we were not copying the owner field from of_platform_driver, so do
the same with it.

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>