can: fix build dependency

Arnd Bergmann's patch [1] fixed the build dependency problem introduced by
bugfix commit cb2dc6d ("can: Kconfig: select CAN driver infrastructure
by default"). This ended up as commit 6abd457 ("can: fix build
dependency"), but I broke Arnd's fix by removing a dependency that we
thought was superfluous.

[1] https://lore.kernel.org/all/20251204100015.1033688-1-arnd@kernel.org/

Meanwhile the problem was also found by intel's kernel test robot,
complaining about undefined symbols:

| ERROR: modpost: "m_can_class_unregister" [drivers/net/can/m_can/m_can_platform.ko] undefined!
| ERROR: modpost: "m_can_class_free_dev" [drivers/net/can/m_can/m_can_platform.ko] undefined!
| ERROR: modpost: "m_can_class_allocate_dev" [drivers/net/can/m_can/m_can_platform.ko] undefined!
| ERROR: modpost: "m_can_class_get_clocks" [drivers/net/can/m_can/m_can_platform.ko] undefined!
| ERROR: modpost: "m_can_class_register" [drivers/net/can/m_can/m_can_platform.ko] undefined!

To fix this problem, add the missing dependency again.

Cc: Vincent Mailhol <mailhol@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512132253.vO9WFDJK-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202512180808.fTAUQ2XN-lkp@intel.com/
Reported-by: Arnd Bergmann <arnd@arndb.de>
Closes: https://lore.kernel.org/all/7427949a-ea7d-4854-9fe4-e01db7d878c7@app.fastmail.com/
Fixes: 6abd457 ("can: fix build dependency")
Fixes: cb2dc6d ("can: Kconfig: select CAN driver infrastructure by default")
Acked-by: Vincent Mailhol <mailhol@kernel.org>
Link: https://patch.msgid.link/20251217-can-fix-dependency-v1-1-fd2d4f2a2bf5@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

Author: marckleinebudde

drivers/net/can/Kconfig

@@ -17,7 +17,7 @@ menuconfig CAN_DEV
 	  virtual ones. If you own such devices or plan to use the virtual CAN
 	  interfaces to develop applications, say Y here.
 
-if CAN_DEV
+if CAN_DEV && CAN
 
 config CAN_VCAN
 	tristate "Virtual Local CAN Interface (vcan)"