net: pch_gbe: CPU accessible addresses are virtual

Use the virt_to_bus & bus_to_virt functions rather than phys_to_bus &
bus_to_phys, since the addresses accessed by the CPU will be virtual
rather than physical. On MIPS physical & virtual addresses differ as we
use virtual addresses in kseg0, and attempting to use physical addresses
directly caused problems as they're in the user segment which would be
mapped via the uninitialised TLB.

Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Signed-off-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>