[RFC]: can-next 2021-04-06: c_can cleanup and mcp251xfd features

[Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>]

Hello,

this series first brings a trivial c_can cleanup that removes an
unused enum. The other patches bring features to the mcp251xfd driver.
Frist BQL support is added again, hopefully working now. The last two
patches try to work around a CRC read error on the TBC register. See
patch description of patch 4 for details.

regards,
Marc