ide: add "ignore_cable" parameter (take 2)

Add "ignore_cable" parameter:

* "ide_core.ignore_cable=[interface_number]" boot option if IDE is built-in
  (i.e. "ide_core.ignore_cable=1" to force ignoring cable for "ide1")

* "ignore_cable=[interface_number]" module parameter (for ide_core module)
  if IDE is compiled as module

v2:
* Add ide_port_apply_params() helper
  - use it in ide_device_add_all() and ide_scan_port().

* Make it possible to later disable ignoring cable detection by passing
  "[interface_number]:0" to /sys/module/ide_core/parameters/ignore_cable
  (however sysfs interface is not enabled yet since it needs some other
   IDE changes to make it work reliable).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/include/linux/ide.h b/include/linux/ide.h
index f0af504..f80d303 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -1222,6 +1222,8 @@
 
 void ide_undecoded_slave(ide_drive_t *);
 
+void ide_port_apply_params(ide_hwif_t *);
+
 int ide_device_add_all(u8 *idx, const struct ide_port_info *);
 int ide_device_add(u8 idx[4], const struct ide_port_info *);
 int ide_legacy_device_add(const struct ide_port_info *, unsigned long);