can: netlink: Fix TDCO calculation using the old data bittiming

The TDCO calculation was done using the currently applied data bittiming,
instead of the newly computed data bittiming, which means that the TDCO
had an invalid value unless setting the same data bittiming twice.

Fixes: d99755f7

 ("can: netlink: add interface for CAN-FD Transmitter Delay Compensation (TDC)")
Signed-off-by: Maxime Jayat <maxime.jayat@mobile-devices.fr>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/all/40579c18-63c0-43a4-8d4c-f3a6c1c0b417@munic.io
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>