ide: convert ide-timing.h to ide-timings.c library (take 2)

* Don't include ide-timing.h in cs5535 and sis5513 host drivers
  (they don't need it currently).

* Convert ide-timing.h to ide-timings.c library and add CONFIG_IDE_TIMINGS
  config option to be selected by host drivers using the library.

While at it:

- fix ide_timing_find_mode() placement

v2:
* Add missing EXPORT_SYMBOLs. (Stephen Rothwell <sfr@canb.auug.org.au>)

There should be no functional changes caused by this patch.

Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/include/linux/ide.h b/include/linux/ide.h
index 81c6ea4..057001f 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -1299,6 +1299,11 @@
 				  IDE_TIMING_CYCLE | IDE_TIMING_UDMA,
 };
 
+struct ide_timing *ide_timing_find_mode(u8);
+void ide_timing_merge(struct ide_timing *, struct ide_timing *,
+		      struct ide_timing *, unsigned int);
+int ide_timing_compute(ide_drive_t *, u8, struct ide_timing *, int, int);
+
 typedef struct ide_pio_timings_s {
 	int	setup_time;	/* Address setup (ns) minimum */
 	int	active_time;	/* Active pulse (ns) minimum */