Update Linux to v5.4.148

Sourced from [1]

[1] https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.4.148.tar.gz

Change-Id: Ib3d26c5ba9b022e2e03533005c4fed4d7c30b61b
Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c
index 00099a8..c6a1d8c 100644
--- a/drivers/tty/pty.c
+++ b/drivers/tty/pty.c
@@ -120,10 +120,10 @@
 		spin_lock_irqsave(&to->port->lock, flags);
 		/* Stuff the data into the input queue of the other end */
 		c = tty_insert_flip_string(to->port, buf, c);
+		spin_unlock_irqrestore(&to->port->lock, flags);
 		/* And shovel */
 		if (c)
 			tty_flip_buffer_push(to->port);
-		spin_unlock_irqrestore(&to->port->lock, flags);
 	}
 	return c;
 }