serial: tegra: DT for Adjusted baud rates

Tegra186 chip has a hardware issue resulting in frame errors when
tolerance level for baud rate is negative. Provided entries to adjust
baud rate to be within acceptable range and work with devices that
can send negative baud rate. Also report error when baud rate set is
out of tolerance range of controller updated in device tree.

Signed-off-by: Krishna Yarlagadda <kyarlagadda@nvidia.com>
Link: https://lore.kernel.org/r/1567572187-29820-10-git-send-email-kyarlagadda@nvidia.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>