Description of problem:

viomem device hotunplug fail with pc type machine.

Version-Release number of selected component (if applicable):

kernel-5.14.0-526.el9.x86_64
qemu-kvm-9.1.0-1.el9.x86_64
edk2-ovmf-20240524-8.el9.noarch
seabios-bin-1.16.3-2.el9.noarch
virtio-win-prewhql-266.iso

How reproducible:
100%

Steps to Reproduce:
1. Boot a win10.x64(PC) guest with a viomem device

/usr/libexec/qemu-kvm \
-name 'win10' \
-machine pc \
-nodefaults \
-device VGA,bus=pci.0 \
-blockdev node-name=file_stg1,driver=file,cache.direct=on,cache.no-flush=off,filename=win10-64-virtio.qcow2,aio=threads \
-blockdev node-name=drive_stg1,driver=qcow2,cache.direct=on,cache.no-flush=off,file=file_stg1 \
-device virtio-blk-pci,id=stg1,drive=drive_stg1,bus=pci.0 \
-device virtio-net-pci,mac=9a:36:83:b6:3d:05,id=idJVpmsF,netdev=id23ZUK6,bus=pci.0 \
-netdev tap,id=id23ZUK6,vhost=on,script=/etc/qemu-ifup \
-m 4G,maxmem=80G,slots=20 \
-smp 2,maxcpus=4 \
-cpu 'Skylake-Server' \
-cdrom /home/kvm_autotest_root/iso/windows/virtio-win-prewhql-0.1-266.iso \
-device piix3-usb-uhci,id=usb -device usb-tablet,id=input0 \
-vnc :10 \
-rtc base=localtime,clock=host,driftfix=slew \
-boot order=cdn,once=c,menu=off,strict=off \
-enable-kvm \
-qmp tcp:0:1212,server,nowait \
-monitor stdio \
-object memory-backend-ram,id=vmem0,size=8G \
-device virtio-mem-pci,id=vm0,memdev=vmem0,node=0,requested-size=1G,bus=pci.0 \

2. hotplug a viomem device
HMP
(qemu) object_add memory-backend-ram,id=vmem1,size=8G
(qemu) device_add virtio-mem-pci,id=vm1,memdev=vmem1,requested-size=0,bus=pci.0

3.unplugg this viomem device

(qemu) device_del vm1

Actual results:
(qemu) device_del vm1
Error: virtio-mem device cannot get unplugged while 'unplugged-inaccessible' != 'on'

Expected results:
The viomem device can be hotunplugged successfully(when requested-size=0).

Other information:
1. ALso Test win2016(PC), hit the same problem.