mtd: cfi: Fix fall-through warnings for Clang

In preparation to enable -Wimplicit-fallthrough for Clang, fix multiple
warnings by explicitly adding multiple break statements and a return
instead of letting the code fall through to the next case.

Link: https://github.com/KSPP/linux/issues/115
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Acked-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20210305081933.GA137147@embeddedor

drivers/mtd/chips/cfi_cmdset_0001.c

@@ -2549,6 +2549,7 @@ static int cfi_intelext_suspend(struct mtd_info *mtd)
 			   anyway? The latter for now. */
 			printk(KERN_NOTICE "Flash device refused suspend due to active operation (state %d)\n", chip->state);
 			ret = -EAGAIN;
+			break;
 		case FL_PM_SUSPENDED:
 			break;
 		}

drivers/mtd/chips/cfi_cmdset_0002.c

@@ -902,6 +902,7 @@ static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr
 			/* Someone else might have been playing with it. */
 			goto retry;
 		}
+		return 0;
 
 	case FL_READY:
 	case FL_CFI_QUERY:
@@ -2994,6 +2995,7 @@ static int cfi_amdstd_suspend(struct mtd_info *mtd)
 			 * as the whole point is that nobody can do anything
 			 * with the chip now anyway.
 			 */
+			break;
 		case FL_PM_SUSPENDED:
 			break;
 

drivers/mtd/chips/cfi_cmdset_0020.c

@@ -1332,6 +1332,8 @@ static int cfi_staa_suspend(struct mtd_info *mtd)
 			 * as the whole point is that nobody can do anything
 			 * with the chip now anyway.
 			 */
+			break;
+
 		case FL_PM_SUSPENDED:
 			break;