powerpc+sparc/vio: Modernize driver registration

This makes vio_register_driver() get the module owner & name at compile
time like PCI drivers do, and adds a name pointer directly in struct
vio_driver to avoid having to explicitly initialize the embedded
struct device.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: David S. Miller <davem@davemloft.net>