[ARM] Set coherent DMA mask for Acorn expansion cards

Although expansion cards can't do bus-master DMA, subsystems
want to be able to use coherent memory for DMA purposes to
these cards.  Therefore, set the coherent DMA mask to allow
such memory to be allocated.
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

arch/arm/kernel/ecard.c

@@ -825,6 +825,7 @@ static struct expansion_card *__init ecard_alloc_card(int type, int slot)
 	ec->dev.bus = &ecard_bus_type;
 	ec->dev.dma_mask = &ec->dma_mask;
 	ec->dma_mask = (u64)0xffffffff;
+	ec->dev.coherent_dma_mask = ec->dma_mask;
 
 	if (slot < 4) {
 		ec_set_resource(ec, ECARD_RES_MEMC,