soc: fsl: dpio: avoid stack usage warning

A 1024 byte variable on the stack will warn on any 32-bit architecture
during compile-testing, and is generally a bad idea anyway:

fsl/dpio/dpio-service.c: In function 'dpaa2_io_service_enqueue_multiple_desc_fq':
fsl/dpio/dpio-service.c:495:1: error: the frame size of 1032 bytes is larger than 1024 bytes [-Werror=frame-larger-than=]

There are currently no callers of this function, so I cannot tell whether
dynamic memory allocation is allowed once callers are added. Change
it to kcalloc for now, if anyone gets a warning about calling this in
atomic context after they start using it, they can fix it later.

Link: https://lore.kernel.org/r/20200408185834.434784-1-arnd@arndb.de
Fixes: 9d988097 ("soc: fsl: dpio: Adding QMAN multiple enqueue interface")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

drivers/soc/fsl/dpio/dpio-service.c

@@ -478,12 +478,18 @@ int dpaa2_io_service_enqueue_multiple_desc_fq(struct dpaa2_io *d,
 				const struct dpaa2_fd *fd,
 				int nb)
 {
-	int i;
-	struct qbman_eq_desc ed[32];
+	struct qbman_eq_desc *ed;
+	int i, ret;
+
+	ed = kcalloc(sizeof(struct qbman_eq_desc), 32, GFP_KERNEL);
+	if (!ed)
+		return -ENOMEM;
 
 	d = service_select(d);
-	if (!d)
-		return -ENODEV;
+	if (!d) {
+		ret = -ENODEV;
+		goto out;
+	}
 
 	for (i = 0; i < nb; i++) {
 		qbman_eq_desc_clear(&ed[i]);
@@ -491,7 +497,10 @@ int dpaa2_io_service_enqueue_multiple_desc_fq(struct dpaa2_io *d,
 		qbman_eq_desc_set_fq(&ed[i], fqid[i]);
 	}
 
-	return qbman_swp_enqueue_multiple_desc(d->swp, &ed[0], fd, nb);
+	ret = qbman_swp_enqueue_multiple_desc(d->swp, &ed[0], fd, nb);
+out:
+	kfree(ed);
+	return ret;
 }
 EXPORT_SYMBOL(dpaa2_io_service_enqueue_multiple_desc_fq);