In the last cycle we have renamed some parameters to make it more
consistent across different drivers. This patch is removing the deprecated
pxe_deploy_{kernel, ramdisk} parameters from the code and updating the
documentation accordingly.
Depends-On: I3dcf8df130efc0c2ea35695018bedba31bf0570c
Change-Id: I07eb7ad28929b651cf04ef3955903e4f4ecf9900