Revert "ozwpan: replace alloc_skb with dev_alloc_skb in ozpd.c"

This reverts commit 812eb995.

I shouldn't have applied it, my fault...

Cc: Xenia Ragiadakou <burzalodowa@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>