Fix a bug about socket exsitence check

Fix a bug about socket exsitence check

When getting app startup signal from a child process of launchpad, AMD
tries to connect to the app socket. When calling the aul_initialize() function,
the application sends the APP_NOTIFY_START request to AMD.
While handling the APP_NOTIFY_START command, AMD sets the flag that is
socket_exists of the app status handle.
After this patch is applied, AMD checks whether the socket exists or not
before sending the app request to the application.

Change-Id: I6974e8684f6b5fec3adc0e4fcd63ec4946f14866
Signed-off-by: Hwankyu Jhun <h.jhun@samsung.com>