powerpc/ps3: set_dabr() takes an unsigned long

Also silences this warning:

arch/powerpc/platforms/ps3/setup.c:275: warning: initialization from incompatible pointer type

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Geoff Levand <geoffrey.levand@am.sony.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>