ci: Build a cheza kernel.

ci: Build a cheza kernel.

This is a set of kernel options I've come up with mostly cribbing from
chrome os's kernel config snippet.  We also build an lzma kernel, as
uncompressed kernel is big but lzma is the only compression supported by
the bootloader.  With that image, we have to pack it into a FIT formatted
image+dtb blob.

CONFIG_SUNRPC_DEBUG is added so that you can set "nfsrootdebug" to figure
out what's going wrong with your nfs mount (mine were "both the tcp and
nfsvers options were required, and don't try to use 'default' as the root
path to defer to DHCP's answer because otherwise you get
/tftpboot/default, just use an empty root path which doesn't prepend
/tftpboot.")

Reviewed-by: Kristian H. Kristensen <hoegsberg@google.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5247>