drm/amdkfd: show warning when kfd is locked

During system suspend the kfd driver aquires a lock that prohibits
further kfd actions unless the gpu is resumed. This adds some info which
can be useful while debugging.
Reviewed-by: Oak Zeng <oak.zeng@amd.com>
Reviewed-by: Felix Kuehling <felix.kuehling@amd.com>
Signed-off-by: Rajneesh Bhardwaj <rajneesh.bhardwaj@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdkfd/kfd_chardev.c

@@ -127,6 +127,8 @@ static int kfd_open(struct inode *inode, struct file *filep)
 		return PTR_ERR(process);
 
 	if (kfd_is_locked()) {
+		dev_dbg(kfd_device, "kfd is locked!\n"
+				"process %d unreferenced", process->pasid);
 		kfd_unref_process(process);
 		return -EAGAIN;
 	}