defconfig: sa8155: enable CNSS_GENL

There are multiple wlan drivers for sa8155, enable CNSS_GENL to
support communicating with userspace utilities, such as cnss_diag.

CRs-Fixed: 2381682
Change-Id: I6a15e177a2a2114797259135858249a1afeac72a
Signed-off-by: Yu Wang <yyuwang@codeaurora.org>