storage_backend_rbd: Correct argument order to rbd_create3

The stripe_unit and stripe_count arguments are passed to rbd_create3 in
the wrong order, resulting in a stripe size of 1 byte with 4194304
stripes on newly created RBD volumes.

https://bugzilla.redhat.com/show_bug.cgi?id=1092208Signed-off-by: NSteven McDonald <steven.mcdonald@anchor.net.au>

src/storage/storage_backend_rbd.c

@@ -492,7 +492,7 @@ static int virStorageBackendRBDCreateImage(rados_ioctx_t io,
     uint64_t stripe_unit = 4194304;
 
     if (rbd_create3(io, name, capacity, features, &order,
-                    stripe_count, stripe_unit) < 0) {
+                    stripe_unit, stripe_count) < 0) {
 #else
     if (rbd_create(io, name, capacity, &order) < 0) {
 #endif