can: rcar_canfd: Rename rcar_canfd_setrnc() to rcar_canfd_set_rnc()

Insert an underscore in the function's name, for consistency with other
getter and setter helper functions.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Link: https://patch.msgid.link/9fdc2584ce27b2784ecea76390d2a81eab289d0d.1749655315.git.geert+renesas@glider.be


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