s390/con3270: testing return kzalloc retval

Return value from kzalloc is not tested and
using a null pointer would lead to crash.

Even if this should not happen at this moment, we
may let the system decide if there is a better choice.
Signed-off-by: NPierre Morel <pmorel@linux.vnet.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/char/con3270.c

@@ -606,6 +606,8 @@ con3270_init(void)
 		return PTR_ERR(rp);
 
 	condev = kzalloc(sizeof(struct con3270), GFP_KERNEL | GFP_DMA);
+	if (!condev)
+		return -ENOMEM;
 	condev->view.dev = rp;
 
 	condev->read = raw3270_request_alloc(0);