A few URLs in the README file pointed to the old openpower.xyz Jenkins
server.  That domain no longer exists and appears to have been bought
by a parking service.  Replace them with URLs to the openbmc.org Jenkins
server and point to corresponding jobs (which have different names).

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I8341f390a154172972f8c3b40228fe20706d7ac7