recovery: fstab: mark /system as being ext4

No longer using squashfs.

Bug: 29622054
Change-Id: I90a388219fdf720f853b0702bef643bb87e6032f
diff --git a/recovery.fstab b/recovery.fstab
index 0ae4a32..1bf6701 100644
--- a/recovery.fstab
+++ b/recovery.fstab
@@ -3,7 +3,7 @@
 /dev/block/by-name/splashscreen /splashscreen emmc     defaults                                                                defaults
 /dev/block/by-name/fastboot     /fastboot     emmc     defaults                                                                defaults
 /dev/block/by-name/misc         /misc         emmc     defaults                                                                defaults
-/dev/block/by-name/system       /system       squashfs     ro                                                                  wait
+/dev/block/by-name/system       /system       ext4     ro,noatime                                                              wait
 /dev/block/by-name/cache        /cache        ext4     nosuid,nodev,noatime,barrier=1,data=ordered                             wait,check
 /dev/block/by-name/userdata     /data         ext4     nosuid,nodev,noatime,discard,barrier=1,data=ordered,noauto_da_alloc     wait,check
 /dev/block/by-name/factory      /factory      ext4     nosuid,nodev,noatime,barrier=1,data=ordered                             wait