net: zynq_gem: Added 64-bit addressing support

This patch adds 64-bit addressing support for zynq gem.
This means it can perform send and receive operations on
64-bit address buffers.

Signed-off-by: Vipul Kumar <vipul.kumar@xilinx.com>
Signed-off-by: Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Michal Simek <monstr@monstr.eu>