dmaengine: Introduce min burst length capability

Some hardware aside from default 0/1 may have greater minimum burst
transactions length constraints. Here we introduce the DMA device
and slave capability, which if required can be initialized by the DMA
engine driver with the device-specific value.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20200723005848.31907-4-Sergey.Semin@baikalelectronics.ru


Signed-off-by: Vinod Koul <vkoul@kernel.org>