soc: ti: knav_dma: Use proper enum in pktdma_init_chan

soc: ti: knav_dma: Use proper enum in pktdma_init_chan

Clang warns when one enumerated type is implicitly converted to another:

drivers/soc/ti/knav_dma.c:601:20: warning: implicit conversion from
enumeration type 'enum dma_data_direction' to different enumeration type
'enum dma_transfer_direction' [-Wenum-conversion]
        chan->direction = DMA_NONE;
                        ~ ^~~~~~~~
1 warning generated.

While DMA_NONE and DMA_TRANS_NONE have different values, there is no
functional change because direction is never checked against DMA_NONE,
only against DMA_MEM_TO_DEV and DMA_DEV_TO_MEM.

Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>