can: mscan: Fix Kconfig dependencies

The only driver based on MSCAN at the moment is for PPC machines,
so it makes no sense to present the menu on M68K. The menu will always
be empty there.
Signed-off-by: NJean Delvare <jdelvare@suse.de>
Cc: Wolfgang Grandegger <wg@grandegger.com>
Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: NMarc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/mscan/Kconfig

 config CAN_MSCAN
-	depends on PPC || M68K
+	depends on PPC
 	tristate "Support for Freescale MSCAN based chips"
 	---help---
 	  The Motorola Scalable Controller Area Network (MSCAN) definition