ide: add IDE_HFLAG_NO_DSC host flag

* Add IDE_HFLAG_NO_DSC host flag for hosts that doesn't support DSC overlap.

* Set it in aec62xx (for ATP850UF only) and hpt34x host drivers.

* Convert ide-tape device driver to check for IDE_HFLAG_NO_DSC flag.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/include/linux/ide.h b/include/linux/ide.h
index 1b31597..af352cc 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -1095,6 +1095,8 @@
 	IDE_HFLAG_CY82C693		= (1 << 27),
 	/* force host out of "simplex" mode */
 	IDE_HFLAG_CLEAR_SIMPLEX		= (1 << 28),
+	/* DSC overlap is unsupported */
+	IDE_HFLAG_NO_DSC		= (1 << 29),
 };
 
 #ifdef CONFIG_BLK_DEV_OFFBOARD