riscv: Add device tree bindings for SPI

This patch adds bindings for the MMC slot and SPI flash on the Sipeed Maix
Bit.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Acked-by: Rick Chen <rick@andestech.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
diff --git a/arch/riscv/dts/k210.dtsi b/arch/riscv/dts/k210.dtsi
index fce98b0..81b0401 100644
--- a/arch/riscv/dts/k210.dtsi
+++ b/arch/riscv/dts/k210.dtsi
@@ -496,6 +496,8 @@
 				interrupts = <24>;
 				clocks = <&sysclk K210_CLK_DVP>;
 				resets = <&sysrst K210_RST_DVP>;
+				kendryte,sysctl = <&sysctl>;
+				kendryte,misc-offset = <K210_SYSCTL_MISC>;
 				status = "disabled";
 			};