powerpc/ps3: Set driver coherent_dma_mask

Set the coherent_dma_mask for the PS3 ehci, ohci, and snd devices.

Silences WARN_ON_ONCE messages emitted by the dma_alloc_attrs() routine.

Reported-by: Fredrik Noring <noring@nocrew.org>
Signed-off-by: Geoff Levand <geoff@infradead.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>