This patch increments privatecnt value and set DMA_PRIVATE in device
caps in dma_request_slave_channel() function. This is needed to keep
privatecnt increment/decrement balance.

As function dma_release_channel() decrements privatecnt counter, we need
to increment it when channel is requested. Otherwise privatecnt drops
into negatives after few dma_release_channel() calls.
Reported-by: NKrzysztof Kozlowski <k.kozlowski@samsung.com>
Signed-off-by: NRobert Baldyga <r.baldyga@samsung.com>
Signed-off-by: NVinod Koul <vinod.koul@intel.com>