cpufreq-dt: fix handling regulator_get_voltage() result

The function can return negative values so it should be assigned
to signed type.

The problem has been detected using proposed semantic patch
scripts/coccinelle/tests/unsigned_lesser_than_zero.cocci.

Link: http://permalink.gmane.org/gmane.linux.kernel/2038576
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
(cherry picked from commit 929ca89c305a6ed7a4149115be99af6d73c36918)
Signed-off-by: Alex Shi <alex.shi@linaro.org>

Author: Andrzej Hajda

drivers/cpufreq/cpufreq-dt.c

@@ -50,7 +50,8 @@ static int set_target(struct cpufreq_policy *policy, unsigned int index)
 	struct private_data *priv = policy->driver_data;
 	struct device *cpu_dev = priv->cpu_dev;
 	struct regulator *cpu_reg = priv->cpu_reg;
-	unsigned long volt = 0, volt_old = 0, tol = 0;
+	unsigned long volt = 0, tol = 0;
+	int volt_old = 0;
 	unsigned int old_freq, new_freq;
 	long freq_Hz, freq_exact;
 	int ret;
@@ -83,7 +84,7 @@ static int set_target(struct cpufreq_policy *policy, unsigned int index)
 			opp_freq / 1000, volt);
 	}
 
-	dev_dbg(cpu_dev, "%u MHz, %ld mV --> %u MHz, %ld mV\n",
+	dev_dbg(cpu_dev, "%u MHz, %d mV --> %u MHz, %ld mV\n",
 		old_freq / 1000, (volt_old > 0) ? volt_old / 1000 : -1,
 		new_freq / 1000, volt ? volt / 1000 : -1);