Currently, dma_alloc_coherent is being called with a GFP_KERNEL
flag which allows it to sleep in an interrupt context, need to
change to GFP_ATOMIC.

Cc: stable@vger.kernel.org
Tested-by: NSteven Royer <seroyer@linux.vnet.ibm.com>
Reviewed-by: NMichael Cyr <mikecyr@linux.vnet.ibm.com>
Signed-off-by: NBryant G. Ly <bryantly@linux.vnet.ibm.com>
Signed-off-by: NBart Van Assche <bart.vanassche@sandisk.com>