DMA: PL330: move filter function into driver

The dma channel selection filter function is moved from plat-samsung
into the pl330 driver. In additon to that, a check is added in the
filter function to ensure that the channel on which the filter has
been invoked is pl330 channel instance (and avoid any incorrect
access of chan->private in a system with multiple types of DMA
drivers).

Suggested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Thomas Abraham <thomas.abraham@linaro.org>
Acked-by: Jassi Brar <jassisinghbrar@gmail.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>