defconfig: Enable cnss_genl driver compilation

cnss_genl driver creates a netlink family and multicast groups
to facilitate communication between WLAN driver and userspace.
Define flag CONFIG_CNSS_GENL and set to 'y'(yes) to enable
compilation of the cnss_genl driver inorder to use the same.

Signed-off-by: Sandeep Singh <sandsing@codeaurora.org>
Change-Id: I6ba6412eb702a456fc02a84a984ea95962269b24
CRs-Fixed: 2346674