Fix a negative mPendingTrackerCount issue

If an user has set permission to PREMIUM_SMS_PERMISSION_NEVER_ALLOW
already, no need to decrease mPendingTrackerCount when stop sending. New
EVENT_SENDING_NOT_ALLOWED is issued to just stop sending without it.

Test: Manual

Change-Id: I80de2b700bd9a7fe58442deacd7d8de1ffd5cd35
Signed-off-by: Taesu Lee <taesu82.lee@samsung.com>