ehea/ibm*: Move the IBM drivers

Move the IBM drivers into drivers/net/ethernet/ibm/ and make the
necessary Kconfig and Makefile changes.

- Renamed ibm_new_emac to emac
- Cleaned up Makefile and Kconfig options which referred to
  IBM_NEW_EMAC to IBM_EMAC
- ibmlana driver is a National Semiconductor SONIC driver so
  it was not moved

CC: Christoph Raisch <raisch@de.ibm.com>
CC: Santiago Leon <santil@linux.vnet.ibm.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: David Gibson <dwg@au1.ibm.com>
CC: Kyle Lucke <klucke@us.ibm.com>
CC: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>