can: CAN_BXCAN should depend on ARCH_STM32

The STMicroelectronics STM32 basic extended CAN Controller (bxCAN) is
only present on STM32 SoCs.  Hence drop the "|| OF" part from its
dependency rule, to prevent asking the user about this driver when
configuring a kernel without STM32 SoC support.

Fixes: f00647d8

 ("can: bxcan: add support for ST bxCAN controller")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Link: https://lore.kernel.org/all/40095112efd1b2214e4223109fd9f0c6d0158a2d.1680609318.git.geert+renesas@glider.be
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>