Workaround: Enable RAM FS on ST boards

Flash on ST boards in CI LAVA is broken, which would cause unexpected PS
test error and get Open CI blocked.
Enable RAM FS for the time being to unblock CI.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: Ie6b622f85dd162b340c0380b8d3689d2c45001d4
1 file changed