Os boot issues on 9p filesystem due to unix domain sockets open failure
Description of problem:
Unix filesystem API is broken, unix domain socket special files return an error at open()
Steps to reproduce:
Simple script. Tries to use netcat to get data through a local unix domain socket file   
```
#!/bin/bash

# Cleanup target dir
[ -d ./target ] && rm -rf target
mkdir target

# Add configuration updates
mkdir -p ./target/etc/initramfs-tools/
echo 9p >> ./target/etc/initramfs-tools/modules
echo 9pnet_virtio >> ./target/etc/initramfs-tools/modules

# Add the test script
cat > ./target/test_init << EOF
#!/bin/bash

echo "Test for unix domain sockets"

nc -Ul /socket &
sleep 1
echo "Sockets work" | nc -UN /socket || echo "Sockets fail"

echo o > /proc/sysrq-trigger
sleep 999
EOF
chmod 700 ./target/test_init

# Create an Ubuntu 23.10 around it
echo "Creating Ubuntu target OS"
debootstrap --variant=minbase\
            --include=udev,kmod,initramfs-tools,systemd,netcat-openbsd,linux-image-generic \
            --exclude=man,bash-completion \
            mantic ./target > /dev/null || exit 1

# Run the test in 9p forwarded filesystem
echo "Running OS in qemu"
qemu-system-s390x \
  -m 8192 \
  -smp 4 \
  -nodefaults -nographic -no-reboot -no-user-config \
  -kernel ./target/boot/vmlinuz \
  -initrd ./target/boot/initrd.img \
  -append 'root=fsRoot rw rootfstype=9p rootflags=trans=virtio,version=9p2000.L,msize=512000,cache=mmap,posixacl console=ttysclp0 init=/test_init quiet' \
  -fsdev local,security_model=passthrough,multidevs=remap,id=fsdev-fsRoot,path=./target \
  -device virtio-9p-pci,id=fsRoot,fsdev=fsdev-fsRoot,mount_tag=fsRoot \
  -device virtio-serial-ccw -device sclpconsole,chardev=console \
  -chardev stdio,id=console,signal=off 
```
Additional information:
Test output:
```
Test for unix domain sockets
qemu-system-s390x: 9p: broken or compromised client detected; attempt to open special file (i.e. neither regular file, nor directory)
nc: No such device or address
nc: /socket: No such file or directory
Sockets fail
```