block: remove BLOCK_OPT_NOCOW from vdi_create_opts

In commit 70747862, the need for NOCOW was removed from the vdi driver,
as we removed the the posix calls.  However, the BLOCK_OPT_NOCOW was not
removed from vdi_create_opts.  This was a mistake - remove the opt from
there as well.
Signed-off-by: NJeff Cody <jcody@redhat.com>
Reviewed-by: NMax Reitz <mreitz@redhat.com>
Reviewed-by: NStefan Weil <sw@weilnetz.de>
Message-id: e189364de11929d8fa04722f5d845de0a9834d44.1417620301.git.jcody@redhat.com
Signed-off-by: NMax Reitz <mreitz@redhat.com>
Signed-off-by: NKevin Wolf <kwolf@redhat.com>

block/vdi.c

@@ -852,11 +852,6 @@ static QemuOptsList vdi_create_opts = {
             .def_value_str = "off"
         },
 #endif
-        {
-            .name = BLOCK_OPT_NOCOW,
-            .type = QEMU_OPT_BOOL,
-            .help = "Turn off copy-on-write (valid only on btrfs)"
-        },
         /* TODO: An additional option to set UUID values might be useful. */
         { /* end of list */ }
     }