Cap memory at 2GB on ppc64 partitioned boxes.

We cap memory at 2GB for the non partitioned case but
forgot to do the same for partitioned boxes.

Signed-off-by: Anton Blanchard <anton@samba.org>
Don't force 32bit build

Now kexec-lite builds and runs 64bit, there is no need to force
the build to be 32bit.

Signed-off-by: Anton Blanchard <anton@samba.org>