spi: renesas: Make driver available on R-Car Gen4

Use CONFIG_RCAR_64 to make the driver available on both
R-Car Gen3 and R-Car Gen4.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
1 file changed