linux-phytec-ti

MAINTAINERS: Update mailing list name for Xen pieces.

While the 'xen-devel@lists.xen.org' is more apt, it is not yet
ready. Revert the name back to the old lists.xensource.com for
right now.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>