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>
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index cdd2304..b1d4b6c 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -381,7 +381,7 @@
 
 config RENESAS_RPC_SPI
 	bool "Renesas RPC SPI driver"
-	depends on RCAR_GEN3 || RZA1
+	depends on RCAR_64 || RZA1
 	imply SPI_FLASH_BAR
 	help
 	  Enable the Renesas RPC SPI driver, used to access SPI NOR flash