clk: clk-wm831x: fix a logic error

Fix bug https://bugzilla.kernel.org/show_bug.cgi?id=188561. Function
wm831x_clkout_is_prepared() returns "true" when it fails to read
CLOCK_CONTROL_1. "true" means the device is already prepared. So
return "true" on the read failure seems improper.

Signed-off-by: Pan Bian <[e-mail]>
Acked-by: Charles Keepax <[e-mail]>
Fixes: f05259a6ffa4 ("clk: wm831x: Add initial WM831x clock driver")
Signed-off-by: Stephen Boyd <[e-mail]>

drivers/clk/clk-wm831x.c

···
 	if (ret < 0) {
 		dev_err(wm831x->dev, "Unable to read CLOCK_CONTROL_1: %d\n",
 			ret);
-		return true;
+		return false;
 	}
 
 	return (ret & WM831X_CLKOUT_ENA) != 0;