[PATCH] add pio_speed

Some drivers need this. Its in the core as the core eventually needs to
be doing the tracking here

include/linux/ide.h

@@ -760,6 +760,7 @@ typedef struct ide_drive_s {
         u8	quirk_list;	/* considered quirky, set for a specific host */
         u8	suspend_reset;	/* drive suspend mode flag, soft-reset recovers */
         u8	init_speed;	/* transfer rate set at boot */
+        u8	pio_speed;      /* unused by core, used by some drivers for fallback from DMA */
         u8	current_speed;	/* current transfer rate set */
         u8	dn;		/* now wide spread use */
         u8	wcache;		/* status of write cache */