virtio-ccw: Include standby memory when calculating storage increment

When determining the memory increment size, use the maxmem size if
it was specified.

Signed-off-by: Matthew Rosato <mjrosato@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
diff --git a/qemu-options.hx b/qemu-options.hx
index c573dd8..9828952 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -225,7 +225,8 @@
     "                size: initial amount of guest memory (default: "
     stringify(DEFAULT_RAM_SIZE) "MiB)\n"
     "                slots: number of hotplug slots (default: none)\n"
-    "                maxmem: maximum amount of guest memory (default: none)\n",
+    "                maxmem: maximum amount of guest memory (default: none)\n"
+    "NOTE: Some architectures might enforce a specific granularity\n",
     QEMU_ARCH_ALL)
 STEXI
 @item -m [size=]@var{megs}