Bluetooth: rfcomm: Remove unnecessary krfcommd event

Removed superfluous event handling which was used to signal
that the rfcomm kthread had been woken. This appears to have been
used to prevent lost wakeups. Correctly ordering when the task
state is set to TASK_INTERRUPTIBLE is sufficient to prevent lost wakeups.

To prevent wakeups which occurred prior to initially setting
TASK_INTERRUPTIBLE from being lost, the main work of the thread loop -
rfcomm_process_sessions() - is performed prior to sleeping.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>