d2-common: tweak fstab

Some boot hangs on d2 have been traced to poor cache performance.
Increase performance by enabling journal_async_commit,noatime, and
noauto_da_alloc. Also remove duplicate definition of /cache in
init.target.rc.

Change-Id: Ic9508cc047256776910160fb9ca1cb2cda183c67
Merge branch 'cm-11.0' into martincz