configs: imx8mn_bsh_smm_s2: add mtdparts to bootargs

Passing the mtdparts environment variable to the Linux kernel is
required to properly mount the UBI rootfs.

Co-developed-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
1 file changed