serial: fsl_lpuart: fix maximum acceptable baud rate with over-sampling

BugLink: https://bugs.launchpad.net/bugs/1822271

[ Upstream commit 815d835b ]

Using over-sampling ratio, lpuart can accept baud rate upto uartclk / 4.
Signed-off-by: Tomonori Sakita <tomonori.sakita@sord.co.jp>
Signed-off-by: Atsushi Nemoto <atsushi.nemoto@sord.co.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Acked-by: Juerg Haefliger <juerg.haefliger@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/tty/serial/fsl_lpuart.c

@@ -1409,7 +1409,7 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
 	}
 
 	/* ask the core to calculate the divisor */
-	baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 16);
+	baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 4);
 
 	spin_lock_irqsave(&sport->port.lock, flags);