qemu-system-sparc64 v8.0.2 failed to read the file system.
Steps to reproduce:
1. Run qemu-system-sparc64 with the following command line.
  `qemu-system-sparc64 -M niagara -L S10image/ -nographic -m 256 -drive if=pflash,readonly=on,file=S10image/disk.s10hw2`
2. The system will report a issue "Could not open option rom 'pflash0': No such file or directory"
3. Then, enter the boot command on the boot loader.
4. The command failed with following message.
```
Boot device: vdisk  File and args:
Bad magic number in disk label
Can't open disk label package

Can't open boot device
```
Additional information:
```
$ qemu-system-sparc64 -M niagara -L S10image/ -nographic -m 256 -drive if=pflash,readonly=on,file=S10image/disk.s10hw2
Could not open option rom 'pflash0': No such file or directory
cpu Probing I/O buses


Sun Fire T2000, No Keyboard
Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
OpenBoot 4.20.0, 256 MB memory available, Serial #1122867.
[mo23723 obp4.20.0 #0]
Ethernet address 0:80:3:de:ad:3, Host ID: 80112233.



ok boot
Boot device: vdisk  File and args:
Bad magic number in disk label
Can't open disk label package

Can't open boot device

ok
```

It works fine with the previous qemu-system-sparc64 version.

```
$ qemu-7.2.3/build/qemu-system-sparc64 -M niagara -L S10image/ -nographic -m 256 -drive if=pflash,readonly=on,file=S10image/disk.s10hw2
cpu Probing I/O buses


Sun Fire T2000, No Keyboard
Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
OpenBoot 4.20.0, 256 MB memory available, Serial #1122867.
[mo23723 obp4.20.0 #0]
Ethernet address 0:80:3:de:ad:3, Host ID: 80112233.



ok boot
Boot device: vdisk  File and args:
Loading ufs-file-system package 1.4 04 Aug 1995 13:02:54.
FCode UFS Reader 1.12 00/07/17 15:48:16.
Loading: /platform/SUNW,Sun-Fire-T2000/ufsboot
Loading: /platform/sun4v/ufsboot
SunOS Release 5.10 Version Generic_118822-23 64-bit
Copyright 1983-2005 Sun Microsystems, Inc.  All rights reserved.
Use is subject to license terms.
Hostname: unknown

unknown console login:
```