tcl/target: add support for Cavium Octeon II CN61xx

Change-Id: Ia14854bc64f5a31b6591be69be4edee9cd1310c3
Signed-off-by: Peter Mamonov <pmamonov@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/5249


Reviewed-by: Oleksij Rempel <linux@rempel-privat.de>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins