soc: ti/knav_dma: include dmaengine header

soc: ti/knav_dma: include dmaengine header

A header file cleanup apparently caused a build regression
with one driver using the knav infrastructure:

In file included from drivers/net/ethernet/ti/netcp_core.c:30:0:
include/linux/soc/ti/knav_dma.h:129:30: error: field 'direction' has incomplete type
  enum dma_transfer_direction direction;
                              ^~~~~~~~~
drivers/net/ethernet/ti/netcp_core.c: In function 'netcp_txpipe_open':
drivers/net/ethernet/ti/netcp_core.c:1349:21: error: 'DMA_MEM_TO_DEV' undeclared (first use in this function); did you mean 'DMA_MEMORY_MAP'?
  config.direction = DMA_MEM_TO_DEV;
                     ^~~~~~~~~~~~~~
                     DMA_MEMORY_MAP
drivers/net/ethernet/ti/netcp_core.c:1349:21: note: each undeclared identifier is reported only once for each function it appears in
drivers/net/ethernet/ti/netcp_core.c: In function 'netcp_setup_navigator_resources':
drivers/net/ethernet/ti/netcp_core.c:1659:22: error: 'DMA_DEV_TO_MEM' undeclared (first use in this function); did you mean 'DMA_DESC_HOST'?
  config.direction  = DMA_DEV_TO_MEM;

As the header is no longer included implicitly through netdevice.h,
we should include it in the header that references the enum.

Fixes: 0dd5759dbb1c ("net: remove dmaengine.h inclusion from netdevice.h")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>