device-fsl

MA-15307 fstab: remove system item in fstab for imx8 a/b platforms

system is mounted before init first stage, no need
mounted in fstab.

Change-Id: I99743cfc06ed4fbc75049c15c8259c117206436f
Signed-off-by: Jindong <jindong.yue@nxp.com>
Reviewed-on: http://androidsource.ap.freescale.net/project/9734
Reviewed-by: zhang sanshan <sanshan.zhang@nxp.com>