net: zynq_gem: Add check for 64-bit dma support by hardware

This patch throws an error if 64-bit support is expected
but DMA hardware is not capable of 64-bit support. It also
prints a debug message if DMA is capable of 64-bit but not
using it.

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>