[BSP] Add network nic command in Linux for vexpress-a9 bsp

bsp/qemu-vexpress-a9/qemu-nographic.sh

@@ -2,5 +2,5 @@ if [ ! -f "sd.bin" ]; then
 dd if=/dev/zero of=sd.bin bs=64M count=1
 fi
 
-qemu-system-arm -M vexpress-a9 -kernel rtthread.elf -nographic -sd sd.bin
+qemu-system-arm -M vexpress-a9 -kernel rtthread.elf -nographic -sd sd.bin -net nic -net tap