DMA-API: provide a helper to setup DMA masks

DMA-API: provide a helper to setup DMA masks

Many drivers contain code such as:

	dev->dma_mask = &dev->coherent_dma_mask;
	dev->coherent_dma_mask = MASK;

Let's move this pattern out of drivers and have the DMA API provide a
helper for it.  This helper uses dma_set_mask_and_coherent() to allow
platform issues to be properly dealt with via dma_set_mask()/
dma_is_supported().

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
(cherry picked from commit fa6a8d6d65b19ab44e5244ea499bcd553cc72343)
Signed-off-by: Ryan Harkin <ryan.harkin@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>