MAINTAINERS: Update MCAN MMIO device driver maintainer

Update Chandrasekar Ramakrishnan as maintainer for mcan mmio device driver as I
will be moving to a different role.

Signed-off-by: Pankaj Sharma <pankj.sharma@samsung.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>