ARM: OMAP: dma: Mark expected switch fall-throughs

Mark switch cases where we are expecting to fall through.

This patch fixes the following warnings:

arch/arm/plat-omap/dma.c: In function 'omap_set_dma_src_burst_mode':
arch/arm/plat-omap/dma.c:384:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (dma_omap2plus()) {
      ^
arch/arm/plat-omap/dma.c:393:2: note: here
  case OMAP_DMA_DATA_BURST_16:
  ^~~~
arch/arm/plat-omap/dma.c:394:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (dma_omap2plus()) {
      ^
arch/arm/plat-omap/dma.c:402:2: note: here
  default:
  ^~~~~~~
arch/arm/plat-omap/dma.c: In function 'omap_set_dma_dest_burst_mode':
arch/arm/plat-omap/dma.c:473:6: warning: this statement may fall through [-Wimplicit-fallthrough=]
   if (dma_omap2plus()) {
      ^
arch/arm/plat-omap/dma.c:481:2: note: here
  default:
  ^~~~~~~

Notice that, in this particular case, the code comment is
modified in accordance with what GCC is expecting to find.
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

arch/arm/plat-omap/dma.c

@@ -388,17 +388,15 @@ void omap_set_dma_src_burst_mode(int lch, enum omap_dma_burst_mode burst_mode)
 		/*
 		 * not supported by current hardware on OMAP1
 		 * w |= (0x03 << 7);
-		 * fall through
 		 */
+		/* fall through */
 	case OMAP_DMA_DATA_BURST_16:
 		if (dma_omap2plus()) {
 			burst = 0x3;
 			break;
 		}
-		/*
-		 * OMAP1 don't support burst 16
-		 * fall through
-		 */
+		/* OMAP1 don't support burst 16 */
+		/* fall through */
 	default:
 		BUG();
 	}
@@ -474,10 +472,8 @@ void omap_set_dma_dest_burst_mode(int lch, enum omap_dma_burst_mode burst_mode)
 			burst = 0x3;
 			break;
 		}
-		/*
-		 * OMAP1 don't support burst 16
-		 * fall through
-		 */
+		/* OMAP1 don't support burst 16 */
+		/* fall through */
 	default:
 		printk(KERN_ERR "Invalid DMA burst mode\n");
 		BUG();