ide: Reject readonly drives unless CD-ROM

drive_init() doesn't permit option readonly for if=ide, but that's
worthless: we get it via if=none and -device.
Signed-off-by: NMarkus Armbruster <armbru@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

hw/ide/core.c

@@ -2617,6 +2617,11 @@ int ide_init_drive(IDEState *s, BlockDriverState *bs,
     if (bdrv_get_type_hint(bs) == BDRV_TYPE_CDROM) {
         s->drive_kind = IDE_CD;
         bdrv_set_change_cb(bs, cdrom_change_cb, s);
+    } else {
+        if (bdrv_is_read_only(bs)) {
+            error_report("Can't use a read-only drive");
+            return -1;
+        }
     }
     if (serial) {
         strncpy(s->drive_serial_str, serial, sizeof(s->drive_serial_str));