can: kvaser_usb: Explicitly initialize family in leafimx driver_info struct

Explicitly set the 'family' driver_info struct member for leafimx.
Previously, the correct operation relied on KVASER_LEAF being the first
defined value in enum kvaser_usb_leaf_family.

Fixes: e6c80e60

 ("can: kvaser_usb: kvaser_usb_leaf: fix CAN clock frequency regression")
Signed-off-by: Jimmy Assarsson <extja@kvaser.com>
Link: https://lore.kernel.org/all/20240628194529.312968-1-extja@kvaser.com
Cc: stable@vger.kernel.org
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>