serial: max310x: set default value when reading clock ready bit

If regmap_read() returns a non-zero value, the 'val' variable can be left
uninitialized.

Clear it before calling regmap_read() to make sure we properly detect
the clock ready bit.

Fixes: 4cf9a888 ("serial: max310x: Check the clock readiness")
Cc: stable@vger.kernel.org
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20240116213001.3691629-2-hugo@hugovil.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/max310x.c

@@ -641,7 +641,7 @@ static u32 max310x_set_ref_clk(struct device *dev, struct max310x_port *s,
 
 	/* Wait for crystal */
 	if (xtal) {
-		unsigned int val;
+		unsigned int val = 0;
 		msleep(10);
 		regmap_read(s->regmap, MAX310X_STS_IRQSTS_REG, &val);
 		if (!(val & MAX310X_STS_CLKREADY_BIT)) {