mfd: Inherit coherent_dma_mask from parent device

dma_mask and dma_parms are already inherited from the parent device but
dma_coherent_mask was left uninitialized (set to zero thanks to kzalloc).
Set sub-device coherent_dma_mask to its parent value to simplify
sub-drivers making use of dma coherent helper functions (those drivers
currently have to explicitly set the dma coherent mask using
dma_set_coherent_mask function).
Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/mfd-core.c

@@ -101,6 +101,7 @@ static int mfd_add_device(struct device *parent, int id,
 	pdev->dev.type = &mfd_dev_type;
 	pdev->dev.dma_mask = parent->dma_mask;
 	pdev->dev.dma_parms = parent->dma_parms;
+	pdev->dev.coherent_dma_mask = parent->coherent_dma_mask;
 
 	ret = regulator_bulk_register_supply_alias(
 			&pdev->dev, cell->parent_supplies,