ide: remove some obsoleted kernel params (v2)

Remove

* "hdx=serialize"
* "idex=noautotune"
* "idex=autotune"

kernel params, they have been obsoleted for ages.

"idex=serialize", "hdx=noautotune" and "hdx=autotune" are still available
so there is no funcionality loss caused by this patch.

v2:

* fix CONFIG_BLK_DEV_4DRIVES=y build broken by version 1 of the patch
  [ /me wearing brown paper bag ]

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/pci/opti621.c b/drivers/ide/pci/opti621.c
index af9aaaf..aede7ee 100644
--- a/drivers/ide/pci/opti621.c
+++ b/drivers/ide/pci/opti621.c
@@ -57,7 +57,7 @@
  * There is a 25/33MHz switch in configuration
  * register, but driver is written for use at any frequency which get
  * (use idebus=xx to select PCI bus speed).
- * Use ide0=autotune for automatical tune of the PIO modes.
+ * Use hda=autotune and hdb=autotune for automatical tune of the PIO modes.
  * If you get strange results, do not use this and set PIO manually
  * by hdparm.
  *