/dev/mem: Mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/mem.c

@@ -765,6 +765,7 @@ static loff_t memory_lseek(struct file *file, loff_t offset, int orig)
 	switch (orig) {
 	case SEEK_CUR:
 		offset += file->f_pos;
+		/* fall through */
 	case SEEK_SET:
 		/* to avoid userland mistaking f_pos=-9 as -EBADF=-9 */
 		if ((unsigned long long)offset >= -MAX_ERRNO) {