arm64: rockchip_defconfig: enable TCP SYN_COOKIES

solve some vst video apk can't play video with kmsg:
"TCP: request_sock_TCP: Possible SYN flooding on port 9000. Dropping request.  Check SNMP counters."

Change-Id: I4fc94307195464c8e8180217eccb9a590eb3c5b6
Signed-off-by: huweiguo <hwg@rock-chips.com>

Author: huweiguo

arch/arm64/configs/rockchip_defconfig

@@ -102,6 +102,7 @@ CONFIG_IP_MULTIPLE_TABLES=y
 CONFIG_IP_ROUTE_VERBOSE=y
 CONFIG_IP_PNP=y
 CONFIG_IP_PNP_DHCP=y
+CONFIG_SYN_COOKIES=y
 CONFIG_INET_AH=y
 CONFIG_INET_ESP=y
 CONFIG_INET_IPCOMP=y