drm/amd/amdgpu: Fix up locking etc in amdgpu_debugfs_gprwave_ioctl()

There are two bugs here.
1) Drop the lock if copy_from_user() fails.
2) If the copy fails then the correct error code is -EFAULT instead of
   -EINVAL.

I also broke up the long line and changed "sizeof rd->id" to
"sizeof(rd->id)".

Fixes: 553f973 ("drm/amd/amdgpu: Update debugfs for XCC support (v3)")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c

@@ -478,15 +478,16 @@ static ssize_t amdgpu_debugfs_gprwave_read(struct file *f, char __user *buf, siz
 static long amdgpu_debugfs_gprwave_ioctl(struct file *f, unsigned int cmd, unsigned long data)
 {
 	struct amdgpu_debugfs_gprwave_data *rd = f->private_data;
-	int r;
+	int r = 0;
 
 	mutex_lock(&rd->lock);
 
 	switch (cmd) {
 	case AMDGPU_DEBUGFS_GPRWAVE_IOC_SET_STATE:
-		r = copy_from_user(&rd->id, (struct amdgpu_debugfs_gprwave_iocdata *)data, sizeof rd->id);
-		if (r)
-			return r ? -EINVAL : 0;
+		if (copy_from_user(&rd->id,
+				   (struct amdgpu_debugfs_gprwave_iocdata *)data,
+				   sizeof(rd->id)))
+			r = -EFAULT;
 		goto done;
 	default:
 		r = -EINVAL;