serrano: Move system to top of fstab list

* As per info it should be mounted first since it contains
  the filesystem check utility. Also remove barrier=1 flag
  since it's the default anyway.

Change-Id: I8815e4a993cdf51c97574f36f5c76591610259ff
Merge branch 'cm-11.0' of https://github.com/CyanogenMod/android_device_samsung_serrano-common into kk_mkt