coresight: Remove function coresight_vpid_to_pid()

Now that we prevent users from using contextID tracing when PID namespaces
are involved there is no client for function coresight_vpid_to_pid().  As
such simply remove it.
Signed-off-by: NMathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: NKim Phillips <kim.phillips@arm.com>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

include/linux/coresight.h

@@ -267,24 +267,4 @@ static inline struct coresight_platform_data *of_get_coresight_platform_data(
 	struct device *dev, const struct device_node *node) { return NULL; }
 #endif
 
-#ifdef CONFIG_PID_NS
-static inline unsigned long
-coresight_vpid_to_pid(unsigned long vpid)
-{
-	struct task_struct *task = NULL;
-	unsigned long pid = 0;
-
-	rcu_read_lock();
-	task = find_task_by_vpid(vpid);
-	if (task)
-		pid = task_pid_nr(task);
-	rcu_read_unlock();
-
-	return pid;
-}
-#else
-static inline unsigned long
-coresight_vpid_to_pid(unsigned long vpid) { return vpid; }
-#endif
-
 #endif