cpufreq: cppc: Fix invalid return value in .get() callback

Returning a negative error code in a function with an unsigned
return type is a pretty bad idea. It is probably worse when the
justification for the change is "our static analisys tool found it".

Fixes: cf7de25878a1 ("cppc_cpufreq: Fix possible null pointer dereference")
Signed-off-by: Marc Zyngier <[e-mail]>
Cc: "Rafael J. Wysocki" <[e-mail]>
Cc: Viresh Kumar <[e-mail]>
Reviewed-by: Lifeng Zheng <[e-mail]>
Signed-off-by: Viresh Kumar <[e-mail]>

drivers/cpufreq/cppc_cpufreq.c

···
 	int ret;
 
 	if (!policy)
-		return -ENODEV;
+		return 0;
 
 	cpu_data = policy->driver_data;