kset: convert parisc/pdc_stable.c to use kset_create

Dynamically create the kset instead of declaring it statically.
This makes the kobject attributes now work properly that I broke in the
previous patch.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Thibaut VARENE <varenet@parisc-linux.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Grant Grundler <grundler@parisc-linux.org>
Cc: Kyle McMartin <kyle@parisc-linux.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>