dmaengine: hsu: Revert "set HSU_CH_MTSR to memory width"

The commit

  080edf75 ("dmaengine: hsu: set HSU_CH_MTSR to memory width")

has been mistakenly submitted. The further investigations show that
the original code does better job since the memory side transfer size
has never been configured by DMA users.

As per latest revision of documentation: "Channel minimum transfer size
(CHnMTSR)... For IOSF UART, maximum value that can be programmed is 64 and
minimum value that can be programmed is 1."

This reverts commit 080edf75.

Fixes: 080edf75

 ("dmaengine: hsu: set HSU_CH_MTSR to memory width")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>