serial: 8250_dw: Simplify the ref clock rate setting procedure

Really instead of twice checking the clk_round_rate() return value
we could do it once, and if it isn't error the clock rate can be changed.
By doing so we decrease a number of ret-value tests and remove a weird
goto-based construction implemented in the dw8250_set_termios() method.
Signed-off-by: NSerge Semin <Sergey.Semin@baikalelectronics.ru>

Link: https://lore.kernel.org/r/20200723003357.26897-3-Sergey.Semin@baikalelectronics.ruSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/8250/8250_dw.c

@@ -282,20 +282,13 @@ static void dw8250_set_termios(struct uart_port *p, struct ktermios *termios,
 
 	clk_disable_unprepare(d->clk);
 	rate = clk_round_rate(d->clk, baud * 16);
-	if (rate < 0)
-		ret = rate;
-	else if (rate == 0)
-		ret = -ENOENT;
-	else
+	if (rate > 0) {
 		ret = clk_set_rate(d->clk, rate);
+		if (!ret)
+			p->uartclk = rate;
+	}
 	clk_prepare_enable(d->clk);
 
-	if (ret)
-		goto out;
-
-	p->uartclk = rate;
-
-out:
 	p->status &= ~UPSTAT_AUTOCTS;
 	if (termios->c_cflag & CRTSCTS)
 		p->status |= UPSTAT_AUTOCTS;