linux-imx

nds32: Remove the redundant assignment

For early version, the value of r2 register was used to display
a character on UART when error occurred. Remove these r2 assignments
because we no longer show the character.

Signed-off-by: Zong Li <zong@andestech.com>
Signed-off-by: Greentime Hu <greentime@andestech.com>