net/ethernet: convert drivers/net/ethernet/* to use module_platform_driver()

This patch converts the drivers in drivers/net/ethernet/* to use the
module_platform_driver() macro which makes the code smaller and a bit
simpler.

Cc: "David S. Miller" <davem@davemloft.net>
Cc: Pantelis Antoniou <pantelis.antoniou@gmail.com>
Cc: Vitaly Bordug <vbordug@ru.mvista.com>
Cc: Wan ZongShun <mcuos.com@gmail.com>
Cc: Nicolas Pitre <nico@fluxnic.net>
Cc: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Jiri Pirko <jpirko@redhat.com>
Cc: Daniel Hellstrom <daniel@gaisler.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Tobias Klauser <tklauser@distanz.ch>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Richard Cochran <richard.cochran@omicron.at>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Sebastian Poehn <sebastian.poehn@belden.com>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Cc: "Michał Mirosław" <mirq-linux@rere.qmqm.pl>
Signed-off-by: Axel Lin <axel.lin@gmail.com>
Acked-by: Wan ZongShun <mcuos.com@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>