scsi: ibmvscsi: Use GFP_KERNEL with dma_alloc_coherent() in initialize_event_pool()

During driver probe we allocate a dma region for our event pool.
Currently, zero is passed for the gfp_flags parameter. Driver probe
callbacks are run in process context and we hold no locks so we can sleep
here if necessary.

Fix by passing GFP_KERNEL explicitly to dma_alloc_coherent().

Link: https://lore.kernel.org/r/1547089149-20577-1-git-send-email-tyreld@linux.vnet.ibm.comReviewed-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Tyrel Datwyler <tyreld@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ibmvscsi/ibmvscsi.c

@@ -454,7 +454,7 @@ static int initialize_event_pool(struct event_pool *pool,
 	pool->iu_storage =
 	    dma_alloc_coherent(hostdata->dev,
 			       pool->size * sizeof(*pool->iu_storage),
-			       &pool->iu_token, 0);
+			       &pool->iu_token, GFP_KERNEL);
 	if (!pool->iu_storage) {
 		kfree(pool->events);
 		return -ENOMEM;