virtio_fs: use global variable to define guest memory size #4664

Job	Run time
Cfg lint	11s
Commit style	8s
PR title	1s
Python 3.6	1m 26s
Python 3.9	2m 5s
Cartesian syntax (qemu/tests/cfg/driver_load_stress.cfg)	11s
Cartesian syntax (qemu/tests/cfg/single_driver_install.cfg)	20s
Cartesian syntax (qemu/tests/cfg/virtio_driver_sign_check.cfg)	8s
Cartesian syntax (qemu/tests/cfg/virtio_fs_hotplug.cfg)	8s
Cartesian syntax (qemu/tests/cfg/virtio_fs_multi_users_access.cfg)	9s
Cartesian syntax (qemu/tests/cfg/virtio_fs_multi_vms.cfg)	18s
Cartesian syntax (qemu/tests/cfg/virtio_fs_readonly.cfg)	8s
Cartesian syntax (qemu/tests/cfg/virtio_fs_security_label.cfg)	7s
Cartesian syntax (qemu/tests/cfg/virtio_fs_set_capability.cfg)	11s
Cartesian syntax (qemu/tests/cfg/virtio_fs_share_data.cfg)	8s
Cartesian syntax (qemu/tests/cfg/virtio_fs_share_data_multi_backend.cfg)	10s
Cartesian syntax (qemu/tests/cfg/virtio_fs_winfsp_test.cfg)	9s
Cartesian syntax (qemu/tests/cfg/win_sigverif.cfg)	8s
Cartesian syntax (qemu/tests/cfg/win_virtio_driver_install_from_update.cfg)	8s
Cartesian syntax (qemu/tests/cfg/win_virtio_driver_update_test.cfg)	9s
	6m 23s

Provide feedback