sparc64: remove restriction on VIO device name size

Removes restriction on VIO device's size limit. Since KOBJ_NAME_LEN
has been dropped from kobject, there doesn't seem to be a
restriction on the device name anymore. This limit therefore
doesn't make sense.

Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
Reviewed-by: Liam Merwick <liam.merwick@oracle.com>
Reviewed-by: Shannon Nelson <shannon.nelson@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>