atiixp: hang fix

When the old IDE layer calls into methods in the driver during error
handling it is essentially random whether ide_lock is already held.  This
causes a deadlock in the atiixp driver which also uses ide_lock internally
for locking.

Switch to a private lock instead.

[akpm@osl.org: cleanup]
Signed-off-by: Alan Cox <alan@redhat.com>
Acked-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>