[POWERPC] Assign PDE->data before gluing PDE into /proc tree

Simply replace proc_create and further data assigned with proc_create_data.
No need to check for data!=NULL after that.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Cc: Alexey Dobriyan <adobriyan@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>