can: flexcan: add quirk FLEXCAN_QUIRK_ENABLE_EACEN_RRS

In order to receive RTR frames in the non HW FIFO mode the RSS and EACEN bits
of the reg_ctrl2 have to be activated. As this has no side effect in the FIFO
mode, we do this unconditionally on cores with the reg_ctrl2.

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