MAINTAINERS: Add entry for Texas Instruments DMA drivers

My employment with TI is coming to an end, it is my intention to look after
the DMA drivers I have worked with over the years.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@gmail.com>
Link: https://lore.kernel.org/r/20201215131348.11282-2-peter.ujfalusi@ti.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>