usb: musb: musb_cppi41: Fix cppi41_set_dma_mode() for DA8xx

usb: musb: musb_cppi41: Fix cppi41_set_dma_mode() for DA8xx

BugLink: http://bugs.launchpad.net/bugs/1731951
commit e10c5b0c773efb8643ee89d387d310584ca30830 upstream.

The way to configure the DMA mode on DA8xx is different from DSPS.
Add a new function to configure DMA mode on DA8xx and use a callback
to call the right function based on the platform.

Signed-off-by: Alexandre Bailon <abailon@baylibre.com>
Tested-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>