can: tcan4x5x: rename tcan4x5x.c -> tcan4x5x-core.c

This is a preparation patch to move the regmap related code into a seperate
file. This patch removes the tcan4x5x.c to tcan4x5x-core.c.
Reviewed-by: Dan Murphy <dmurphy@ti.com>
Tested-by: Sean Nyekjaer <sean@geanix.com>
Link: https://lore.kernel.org/r/20201215231746.1132907-4-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/m_can/Makefile

@@ -7,3 +7,6 @@ obj-$(CONFIG_CAN_M_CAN) += m_can.o
 obj-$(CONFIG_CAN_M_CAN_PCI) += m_can_pci.o
 obj-$(CONFIG_CAN_M_CAN_PLATFORM) += m_can_platform.o
 obj-$(CONFIG_CAN_M_CAN_TCAN4X5X) += tcan4x5x.o
+
+tcan4x5x-objs :=
+tcan4x5x-objs += tcan4x5x-core.o