dmaengine: ti: k3-udma: Initial support for K3 BCDMA

One of the DMAs introduced with AM64 is the Block Copy DMA (BCDMA).
It serves similar purpose as K3 UDMAP channels in TR mode.

The rings for the BCDMA is integrated within the DMA itself instead of
using rings from the general purpose ringacc.

A BCDMA have two different type of channels:
- Block Copy Channels (bchan)
- Split Channels (tchan and rchan)

tchan and rchan can be used to service PSI-L peripherals, similarly to
K3 UDMA channels.

bchan can be only used for block copy operation (TR type15) like the
paired K3 UDMA tchan/rchan configured in block copy mode.
bchans can be also used to service peripherals directly if an external
trigger is selected for the channel.

Most of the driver code can be reused for BCDMA bchan/tchan/rchan support
but new setup and allocation functions are needed to handle the
differences between the DMAs.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Link: https://lore.kernel.org/r/20201208090440.31792-18-peter.ujfalusi@ti.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>