linux-phytec-ti

dmaengine: Add function to request slave channel from a dma_device

dma_get_any_slave_channel() would skip using the filter function, which
in some cases needed to be executed before the alloc_chan_resources
callback to make sure that all parameters are provided for the slave
channel.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>