usb: musb: tusb6010_omap: Create new struct for DMA data/parameters

For the DMA we have ch (channel), dmareq and sync_dev parameters both
within the tusb_omap_dma_ch and tusb_omap_dma struct.
By creating a common struct the code can be simplified when selecting
between the shared or multichannel DMA parameters.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>