dmaengine: xgene: buffer overflow in xgene_dma_init_channels()

We put 9 characters into the 8 character name[] array.  Let's make the
array bigger and change the sprintf() to snprintf().

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>