habanalabs: silence an uninitialized variable warning

Smatch warns that:

    drivers/misc/habanalabs/common/command_buffer.c:471 hl_cb_ioctl()
    error: uninitialized symbol 'device_va'.

Which is true, but harmless.  Anyway, it's easy to silence this by
adding a error check.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

drivers/misc/habanalabs/common/command_buffer.c

@@ -464,6 +464,8 @@ int hl_cb_ioctl(struct hl_fpriv *hpriv, void *data)
 				args->in.flags,
 				&usage_cnt,
 				&device_va);
+		if (rc)
+			break;
 
 		memset(&args->out, 0, sizeof(args->out));