pata_legacy: correctly mask recovery field for HT6560B

According to the HT6560H datasheet, the recovery timing field is 4-bit wide,
with a value of 0 meaning 16 cycles. Correct obvious thinko in the recovery
field mask.
Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: stable@kernel.org
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

drivers/ata/pata_legacy.c

@@ -401,8 +401,7 @@ static void ht6560b_set_piomode(struct ata_port *ap, struct ata_device *adev)
 	ata_timing_compute(adev, adev->pio_mode, &t, 20000, 1000);
 
 	active = clamp_val(t.active, 2, 15);
-	recover = clamp_val(t.recover, 2, 16);
-	recover &= 0x15;
+	recover = clamp_val(t.recover, 2, 16) & 0x0F;
 
 	inb(0x3E6);
 	inb(0x3E6);