wctdm24xxp: Eliminate chance for channel to be stuck in RED alarm.

There was a code patch where it was possible to get stuck in RED ALARM on a
channel when debouncing the battery states. The state transitions would look
like this:

BATTERY_PRESENT -> BATTERY_DEBOUNCING_LOST -> BATTERY_DEBOUNCING_LOST_ALARM --
(send alarm up to asterisk) --> BATTERY_LOST -> BATTERY_DEBOUNCING_PRESENT ->
BATTERY_DEBOUNCING_PRESENT_ALARM -> BATTERY_DEBOUNCING_LOST -> BATTERY_PRESENT

In the above sequence there was never any transition from
BATTERY_DEBOUNCING_PRESENT_ALARM to BATTERY_PRESENT so the alarm to Asterisk was
never cleared and the channel stayed stuck.

Now when you loose battery when in the BATTERY_DEBOUNCING_PRESENT_ALARM go all
the way back to the BATTERY_LOST state instead of the BATTERY_DEBOUNCING_LOST
state so that all the events are properly sent up.

Internal-Issue-ID: DAHDI-1019
Signed-off-by: Shaun Ruffell <sruffell@digium.com>