ide: add IDE_HFLAG_CLEAR_SIMPLEX host flag

* Rename 'simplex_stat' variable to 'dma_stat' in ide_get_or_set_dma_base().

* Factor out code for forcing host out of "simplex" mode from
  ide_get_or_set_dma_base() to ide_pci_clear_simplex() helper.

* Add IDE_HFLAG_CLEAR_SIMPLEX host flag and set it in alim15x3 (for M5229),
  amd74xx (for AMD 7409), cmd64x (for CMD643), generic (for Netcell) and
  serverworks (for CSB5) host drivers.

* Make ide_get_or_set_dma_base() test for IDE_HFLAG_CLEAR_SIMPLEX host flag
  instead of checking dev->device (BTW the code was buggy because it didn't
  check for dev->vendor, luckily none of these PCI Device IDs was used by
  some other vendor for PCI IDE controller).

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/include/linux/ide.h b/include/linux/ide.h
index f1a10c8..1b31597 100644
--- a/include/linux/ide.h
+++ b/include/linux/ide.h
@@ -1093,6 +1093,8 @@
 	IDE_HFLAG_ABUSE_SET_DMA_MODE	= (1 << 26),
 	/* host is CY82C693 */
 	IDE_HFLAG_CY82C693		= (1 << 27),
+	/* force host out of "simplex" mode */
+	IDE_HFLAG_CLEAR_SIMPLEX		= (1 << 28),
 };
 
 #ifdef CONFIG_BLK_DEV_OFFBOARD