[REVERT ME] tty-ffl: Change ffl_hangup_wq to be a freezable workqueue

[REVERT ME] tty-ffl: Change ffl_hangup_wq to be a freezable workqueue

BZ:27289

When system goes to s3, tty-ffl might detect a modem TX timeout
and start error recovery before hsi is resumed. The patch
changes workqueue ffl_hangup_wq to be freezable.

Change-Id: I5b9e7b1bffccfc016afd4e373e2ba438a81680a0
Signed-off-by: Yanmin Zhang <yanmin.zhang@intel.com>
Reviewed-on: http://android.intel.com:8080/40789
Reviewed-by: Roulliere, Pierre <pierre.roulliere@intel.com>
Reviewed-by: Chotard, Celine <celine.chotard@intel.com>
Tested-by: Chotard, Celine <celine.chotard@intel.com>
Reviewed-by: Predon, Frederic <frederic.predon@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>