staging: fsl-dpaa2/eth: Fix incorrect casts

The DPAA2 Ethernet driver incorrectly assumes virtual addresses
are always 64b long, which causes compiler errors when building
for a 32b platform.

Fix this by using explicit casts to uintptr_t where necessary.

Signed-off-by: Ioana Radulescu <ruxandra.radulescu@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>