defconfig: sdxlemur: Disable cnss_genl config

wlan_service can't communicate with wlan driver when
cnss_genl is enabled, so the TCP/IP parameters auto-tuning
is not working, KPI can't meet target.

Change-Id: I8e569f8a435704585015f85ce1ca06f5b12a055f
Signed-off-by: Yu Tian <yutian@codeaurora.org>