ide: don't BUG() on unsupported transfer modes

Fix ide-cris, cs5530, sc1200 and sis5513 host drivers to just return instead
of OOPS-ing for unsupported modes in ->set_dma_mode methods.

Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
diff --git a/drivers/ide/cris/ide-cris.c b/drivers/ide/cris/ide-cris.c
index e196aef..7f5bc2e 100644
--- a/drivers/ide/cris/ide-cris.c
+++ b/drivers/ide/cris/ide-cris.c
@@ -748,8 +748,7 @@
 			hold = ATA_DMA2_HOLD;
 			break;
 		default:
-			BUG();
-			break;
+			return;
 	}
 
 	if (speed >= XFER_UDMA_0)
diff --git a/drivers/ide/pci/cs5530.c b/drivers/ide/pci/cs5530.c
index 5994089..5476903 100644
--- a/drivers/ide/pci/cs5530.c
+++ b/drivers/ide/pci/cs5530.c
@@ -117,8 +117,7 @@
 		case XFER_MW_DMA_1:	timings = 0x00012121; break;
 		case XFER_MW_DMA_2:	timings = 0x00002020; break;
 		default:
-			BUG();
-			break;
+			return;
 	}
 	basereg = CS5530_BASEREG(drive->hwif);
 	reg = inl(basereg + 4);			/* get drive0 config register */
diff --git a/drivers/ide/pci/sc1200.c b/drivers/ide/pci/sc1200.c
index 0a7b320..707d5ff 100644
--- a/drivers/ide/pci/sc1200.c
+++ b/drivers/ide/pci/sc1200.c
@@ -186,8 +186,7 @@
 			}
 			break;
 		default:
-			BUG();
-			break;
+			return;
 	}
 
 	if (unit == 0) {			/* are we configuring drive0? */
diff --git a/drivers/ide/pci/sis5513.c b/drivers/ide/pci/sis5513.c
index 6b7bb53..f6e2ab3 100644
--- a/drivers/ide/pci/sis5513.c
+++ b/drivers/ide/pci/sis5513.c
@@ -356,7 +356,6 @@
 			sis_program_timings(drive, speed);
 			break;
 		default:
-			BUG();
 			break;
 	}
 }