can: rcar_can: BCR bitfield conversion

can: rcar_can: BCR bitfield conversion

Convert CAN Bit Configuration Register field accesses to use the
FIELD_PREP() bitfield access macro.  While at it, fix the misspelling of
BRP.

This gets rid of custom function-like field preparation macros.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://patch.msgid.link/01cfaedba2be22515ba8700893ea7f113df959c0.1755857536.git.geert+renesas@glider.be
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>