upgrade gatt connection performence

upgrade gatt connection performence

when autoconnect flag is used in connectGatt(..),
connection speed is better than another flag true
so only first gatt connection will be requested as autoconnect flag false.

and next connect will be requested as auto connect flag true.
so, background connect will be supported by BT platform.

Change-Id: I73425eb61b3411b242845b0e5f86b9f4b726d4d4
Signed-off-by: jihwan.seo <jihwan.seo@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/5079
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Jon A. Cruz <jonc@osg.samsung.com>