vxge: Removed accessing non-supported registers.

- Removed accessing GENDMA_INT register
 - This allowed the firmware to perform a generic DMA write to host memory.
   This feature is not supported by the ASIC, this patch removes access to
   GENDMA_INT register.

Signed-off-by: Sreenivasa Honnur <sreenivasa.honnur@neterion.com>
Signed-off-by: David S. Miller <davem@davemloft.net>