soc: rockchip: add reboot-mode header

Rockchip platform use a SYSCON mapped register store
the reboot mode magic value for bootloader to use when
system reboot.

Add the shared header describing the values firmware expects
for different boot modes.

Signed-off-by: Andy Yan <[e-mail]>
Reviewed-by: Matthias Brugger <[e-mail]>
Signed-off-by: Heiko Stuebner <[e-mail]>

include/dt-bindings/soc/rockchip,boot-mode.h

···
+#ifndef __ROCKCHIP_BOOT_MODE_H
+#define __ROCKCHIP_BOOT_MODE_H
+
+/*high 24 bits is tag, low 8 bits is type*/
+#define REBOOT_FLAG		0x5242C300
+/* normal boot */
+#define BOOT_NORMAL		(REBOOT_FLAG + 0)
+/* enter bootloader rockusb mode */
+#define BOOT_BL_DOWNLOAD	(REBOOT_FLAG + 1)
+/* enter recovery */
+#define BOOT_RECOVERY		(REBOOT_FLAG + 3)
+ /* enter fastboot mode */
+#define BOOT_FASTBOOT		(REBOOT_FLAG + 9)
+
+#endif