Fix a missing close quote in the layer add button, and
use the layer index for the xhr_layer call.
[YOCTO #11213]
(Bitbake rev: 54d61e7c64c97799de85b3563119f0f5d051675e)
Signed-off-by: David Reyna <David.Reyna@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>