[POWERPC] lparcfg: Remove useless buffer allocation

The 'data' member of proc_ppc64_lparcfg is unused, but the lparcfg
module's init routine allocates 4K for it.

Remove the code which allocates and frees this buffer.

Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>