[SCSI] qla4xxx: bug fixes

The included patch fixes the following issues:

1. qla3xxx/qla4xxx co-existence issue which can result in a lockup
when qla3xxx driver is unloaded, or when ifdown; ifup is performed on
one of the interfaces correponding to qla3xxx. This is because qla4xxx
HBA supports one ethernet and iscsi interfaces per port. Both iscsi
and ethernet interfaces share the same state machine. The problem has
to do with synchronizing access to the state machine in the event of a
reset

2. mutex_lock() is sometimes not followed by mutex_unlock() prior to
invoking a msleep() in qla4xxx_mailbox_command()

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>