mfd: si476x-i2c: Fix spelling mistake in case() statement's FALLTHROUGH comment

's/FALLTHROUG/FALLTHROUGH'

Cc: Andrey Smirnov <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/si476x-i2c.c

···
 			goto unknown_revision;
 		}
 	case SI476X_FUNC_BOOTLOADER:
-	default:		/* FALLTHROUG */
+	default:		/* FALLTHROUGH */
 		BUG();
 		return -1;
 	}