cpufreq: ppc_cbe: fix possible object reference leak

The call to of_get_cpu_node returns a node pointer with refcount
incremented thus it must be explicitly decremented after the last
usage.

Detected by coccinelle with the following warnings:
./drivers/cpufreq/ppc_cbe_cpufreq.c:89:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 76, but without a corresponding object release within this function.
./drivers/cpufreq/ppc_cbe_cpufreq.c:89:2-8: ERROR: missing of_node_put; acquired a node pointer with refcount incremented on line 76, but without a corresponding object release within this function.

Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: linux-pm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>

drivers/cpufreq/ppc_cbe_cpufreq.c

@@ -86,6 +86,7 @@ static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	if (!cbe_get_cpu_pmd_regs(policy->cpu) ||
 	    !cbe_get_cpu_mic_tm_regs(policy->cpu)) {
 		pr_info("invalid CBE regs pointers for cpufreq\n");
+		of_node_put(cpu);
 		return -EINVAL;
 	}