If the a new ring layout is set, the max coalesced frames for RX and
TX are re-calculated, too. Add the missing assignment of the newly
calculated TX max coalesced frames.

Fixes: 656fc12d ("can: mcp251xfd: add TX IRQ coalescing ethtool support")
Link: https://lore.kernel.org/all/20230130154334.1578518-1-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>