drm/amdkfd: Correct SMI event read size

sizeof(buf) is 8 bytes because it is defined as unsigned char *buf,
each SMI event read only copy max 8 bytes to user buffer. Correct this
by using the buf allocate size.
Signed-off-by: Philip Yang <Philip.Yang@amd.com>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -82,7 +82,8 @@ static ssize_t kfd_smi_ev_read(struct file *filep, char __user *user,
 	struct kfd_smi_client *client = filep->private_data;
 	unsigned char *buf;
 
-	buf = kmalloc_array(MAX_KFIFO_SIZE, sizeof(*buf), GFP_KERNEL);
+	size = min_t(size_t, size, MAX_KFIFO_SIZE);
+	buf = kmalloc(size, GFP_KERNEL);
 	if (!buf)
 		return -ENOMEM;
 
@@ -96,7 +97,7 @@ static ssize_t kfd_smi_ev_read(struct file *filep, char __user *user,
 		ret = -EAGAIN;
 		goto ret_err;
 	}
-	to_copy = min3(size, sizeof(buf), to_copy);
+	to_copy = min(size, to_copy);
 	ret = kfifo_out(&client->fifo, buf, to_copy);
 	spin_unlock(&client->lock);
 	if (ret <= 0) {