net: e1000: Use virt_to_phys() instead of pci_virt_to_mem()

Using (dm_)pci_virt_to_mem() is incorrect to translate the virtual
address in local DRAM to a physical address. The correct macro here
is virt_to_phys() so switch to using this macro.

As virt_to_bus() is now not used any more, this patch also removes
both definitions (DM and non-DM).

This issue was detected while testing the e1000 driver on the MIPS
Octeon III platform, which needs address translation.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Joe Hershberger <joe.hershberger@ni.com>
Cc: Aaron Williams <awilliams@marvell.com>
Cc: Chandrakala Chavva <cchavva@marvell.com>