can: m_can: remove support for custom bit timing

Since commit aee2b3cc ("can: tcan4x5x: fix bittiming const, use
common bittiming from m_can driver") there is no use of the device
specific bit timing parameters (m_can_classdev::bit_timing and struct
m_can_classdev::data_timing).

This patch removes the support for custom bit timing from the driver,
as the common bit timing works for all known IP core implementations.

Cc: Chandrasekar Ramakrishnan <rcsekar@samsung.com>
Link: https://lore.kernel.org/r/20210616102811.2449426-7-mkl@pengutronix.de


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>