defconfig: sdm845: Enable missing network options

Android Kernel Net Testing requires additional configuration options
to work properly. Enable the following:
        SYN_COOKIES
        INET_UDP_DIAG
        IP_SCTP
        INET_SCTP_DIAG

Change-Id: Ib0805d7105c79774be37c0d0454db7a76a9bb764
Signed-off-by: Sean Tranchetti <stranche@codeaurora.org>
Signed-off-by: Chinmay Agarwal <chinagar@codeaurora.org>