can: cc770: Fix use after free in cc770_tx_interrupt()

commit 9ffd7503944ec7c0ef41c3245d1306c221aef2be upstream.

This fixes use after free introduced by the last cc770 patch.

Signed-off-by: Andri Yngvason <andri.yngvason@marel.com>
Fixes: 746201235b3f ("can: cc770: Fix queue stall & dropped RTR reply")
Cc: linux-stable <stable@vger.kernel.org>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>