can: Kconfig: remove obsolete help text for slcan

Commit cfcb4465 ("can: slcan: remove legacy infrastructure")
removed the 10-device limit.  Update the Kconfig help text accordingly.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://lore.kernel.org/all/20240427152648.25434-1-mans@mansr.comSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/Kconfig

@@ -187,9 +187,8 @@ config CAN_SLCAN
 	  slcand) can be found in the can-utils at the linux-can project, see
 	  https://github.com/linux-can/can-utils for details.
 
-	  The slcan driver supports up to 10 CAN netdevices by default which
-	  can be changed by the 'maxdev=xx' module option. This driver can
-	  also be built as a module. If so, the module will be called slcan.
+	  This driver can also be built as a module. If so, the module
+	  will be called slcan.
 
 config CAN_SUN4I
 	tristate "Allwinner A10 CAN controller"