FlexCAN on i.MX8MP is not derived from i.MX6Q, instead reuses from
i.MX8QM with extra ECC added and default is enabled, so that the FlexCAN
would be put into freeze mode without FLEXCAN_QUIRK_DISABLE_MECR quirk.

This patch removes "fsl,imx6q-flexcan" fallback compatible string since
it's not compatible with the i.MX6Q.

Link: https://lore.kernel.org/r/20210719073437.32078-1-qiangqing.zhang@nxp.comSigned-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>