fs_mgr: Allow remounts with Magisk installed

This allows remount to gracefully mount /system when Magisk
is installed.

As a sidenote, the ro.debuggable property check can safely
be removed due to the simple fact that CPP preprocessor flag
ALLOW_ADBD_DISABLE_VERITY=1 is passed when building
userdebug/eng.

Change-Id: Ic10eccbf5d225468c3dc42f8ae3ae7c05b49a699
1 file changed