samples: net: wifi: nxp: fix TCP RX accept error

Fix the zperf TCP RX accept error when start both UDP and TCP zperf
server, as the fdtable size is not enough and reserve fd table failed.

Signed-off-by: Maochen Wang <maochen.wang@nxp.com>

Author: MaochenWang1

samples/net/wifi/shell/nxp/overlay_hosted_mcu.conf

@@ -11,6 +11,7 @@ CONFIG_SHELL_CMD_BUFF_SIZE=512
 CONFIG_EVENTS=y
 CONFIG_SYS_HEAP_AUTO=y
 CONFIG_SCHED_MULTIQ=y
+CONFIG_ZVFS_OPEN_MAX=30
 
 # AP
 CONFIG_NXP_WIFI_SOFTAP_SUPPORT=y