fmem: clean up tmem metadata before leaving T-state

In a misguided effort to reduce the latency for
the transition from T-state to C-state, clean up
of tmem metadata was postponed until we attempted
to enter T-state again. However, since some of
this metadata was stored in fmem, it was sometimes
overwritten while in C-state, causing panics and hangs.

Change-Id: Ifa1aafaf0782132a6fc1be7beb2c9070352a1385
Signed-off-by: Larry Bassel <lbassel@codeaurora.org>