LAVA: Disable FF test on MPS2 boards

LAVA is reading FF logs from a wrong UART on MPS2 boards.
Disable FF test on MPS2 boards to avoid blocking CI.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: I56a9f4dfac25ba1a96f3a9100f194535ff919fb0
1 file changed