powerpc/ps3: Use dma_addr_t down through the stack

Push the dma_addr_t type usage all the way down to where the actual
values are manipulated.

Now that u64 is "unsigned long long", this removes warnings like:

arch/powerpc/platforms/ps3/system-bus.c:532: warning: passing argument 4 of 'ps3_dma_map' from incompatible pointer type
arch/powerpc/platforms/ps3/system-bus.c:649: warning: passing argument 4 of 'ps3_dma_map' 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>