dma: ti: k3-udma: Add support for native configuration of chan/flow

In absence of Device Manager (DM) services such as at R5 SPL stage,
driver will have to natively setup TCHAN/RCHAN/RFLOW cfg registers.
Add support for the same.

Note that we still need to send chan/flow cfg message to TIFS via TISCI
client driver in order to open up firewalls around chan/flow but setting
up of cfg registers is handled locally.

U-Boot specific code is in a separate file included in main driver so
as to maintain similarity with kernel driver in order to ease porting of
code in future.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210607141753.28796-8-vigneshr@ti.com