dtc2278: fix deadlock on error handling

Stop abusing ide_lock lock (switch to a private locking).

Fixes same issue as fixed by Alan Cox in atiixp host driver with
commit 6c5f8cc3.
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

drivers/ide/legacy/dtc2278.c

@@ -67,18 +67,20 @@ static void sub22 (char b, char c)
 	}
 }
 
+static DEFINE_SPINLOCK(dtc2278_lock);
+
 static void dtc2278_set_pio_mode(ide_drive_t *drive, const u8 pio)
 {
 	unsigned long flags;
 
 	if (pio >= 3) {
-		spin_lock_irqsave(&ide_lock, flags);
+		spin_lock_irqsave(&dtc2278_lock, flags);
 		/*
 		 * This enables PIO mode4 (3?) on the first interface
 		 */
 		sub22(1,0xc3);
 		sub22(0,0xa0);
-		spin_unlock_irqrestore(&ide_lock, flags);
+		spin_unlock_irqrestore(&dtc2278_lock, flags);
 	} else {
 		/* we don't know how to set it back again.. */
 	}