PM / OPP: silence an uninitialized variable warning

Smatch complains that it's possible we print "rate" in the debug output
when it hasn't been initialized.  It should be zero on that path.

Fixes: a1e8c13600bf ("PM / OPP: "opp-hz" is optional for power domains")
[ Viresh: Added the Fixes tag ]
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/opp/of.c

@@ -287,7 +287,7 @@ static int _opp_add_static_v2(struct opp_table *opp_table, struct device *dev,
 			      struct device_node *np)
 {
 	struct dev_pm_opp *new_opp;
-	u64 rate;
+	u64 rate = 0;
 	u32 val;
 	int ret;
 	bool rate_not_available = false;