qapi/hmp: use 'backend' instead of 'device' with memory backend

fixup documentation comments and HMP message/help text

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>




diff --git a/monitor.c b/monitor.c
index c7f8797..8c17f89 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2968,7 +2968,7 @@
         .name       = "memdev",
         .args_type  = "",
         .params     = "",
-        .help       = "show the memory device",
+        .help       = "show memory backends",
         .mhandler.cmd = hmp_info_memdev,
     },
     {