The imx8m also has a Cortex m4 so add a target for it.
Change-Id: I2abf62b6232c547fe9b12507f459835b11c63a6d
Signed-off-by: Angus Ainslie <angus@akkea.ca>
Reviewed-on: http://openocd.zylin.com/4501
Tested-by: jenkins
Reviewed-by: Matthias Welwarsky <matthias@welwarsky.de>