can: rcar_canfd: Fix R-Car V3U GAFLCFG field accesses

can: rcar_canfd: Fix R-Car V3U GAFLCFG field accesses

Each Global Acceptance Filter List Configuration Register (GAFLCFG)
contains two fields, and stores the number of channel rules for one
channel pair.

As R-Car V3U and later can have more than 2 channels, the field
selection should be based on the LSB (even or odd) of the channel
number, instead of on the full channel number.

Fixes: 45721c406dcf50d4 ("can: rcar_canfd: Add support for r8a779a0 SoC")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/all/36bcf0ffb96d6aaed970751f9546b901af638bcf.1674499048.git.geert+renesas@glider.be
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>