defconfig: Enabling config INET_DIAG_DESTROY

Sockets that are opened before VPN is connected
are supposed to be destroyed once it is connected.
VPN related CTS testcases are failing without the
ability to destroy sockets. Enabling INET_DIAG_DESTROY
to fix these testcases.

CRs-Fixed: 1043997
Change-Id: Id816c21edcb6a7e76d9b39cea66ea1201bae8739
Signed-off-by: Devi Sandeep Endluri V V <dendluri@codeaurora.org>