rtc: pcf8563: fix output clock rate

BugLink: http://bugs.launchpad.net/bugs/1745052

[ Upstream commit a3350f9c ]

The pcf8563_clkout_recalc_rate function erroneously ignores the
frequency index read from the CLKO register and always returns
32768 Hz.

Fixes: a39a6405 ("rtc: pcf8563: add CLKOUT to common clock framework")
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

drivers/rtc/rtc-pcf8563.c

@@ -427,7 +427,7 @@ static unsigned long pcf8563_clkout_recalc_rate(struct clk_hw *hw,
 		return 0;
 
 	buf &= PCF8563_REG_CLKO_F_MASK;
-	return clkout_rates[ret];
+	return clkout_rates[buf];
 }
 
 static long pcf8563_clkout_round_rate(struct clk_hw *hw, unsigned long rate,