ide: always set nIEN on idle devices

* Set nIEN for previous port/device in ide_do_request()
  also if port uses a non-shared IRQ.

* Remove no longer needed ide_hwif_t.sharing_irq.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/ide-io.c b/drivers/ide/ide-io.c
index ca51460..f776bd4 100644
--- a/drivers/ide/ide-io.c
+++ b/drivers/ide/ide-io.c
@@ -1003,7 +1003,7 @@
 		}
 	again:
 		hwif = HWIF(drive);
-		if (hwgroup->hwif->sharing_irq && hwif != hwgroup->hwif) {
+		if (hwif != hwgroup->hwif) {
 			/*
 			 * set nIEN for previous hwif, drives in the
 			 * quirk_list may not like intr setups/cleanups