arm: rmobile: Add HopeRun HiHope RZ/G2N board support

The HiHope RZ/G2N board from HopeRun consists of main board
(HopeRun HiHope RZ/G2N main board) and sub board(HopeRun
HiHope RZ/G2N sub board). The HiHope RZ/G2N sub board sits
below the HiHope RZ/G2N main board.

This patch adds the required board support to boot HopeRun HiHope
RZ/G2N board.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
diff --git a/arch/arm/mach-rmobile/Kconfig.64 b/arch/arm/mach-rmobile/Kconfig.64
index 2c2c603..03b9986 100644
--- a/arch/arm/mach-rmobile/Kconfig.64
+++ b/arch/arm/mach-rmobile/Kconfig.64
@@ -104,6 +104,7 @@
 config TARGET_HIHOPE_RZG2
 	bool "HiHope RZ/G2 board"
 	imply R8A774A1
+	imply R8A774B1
 	imply SYS_MALLOC_F
 	imply MULTI_DTB_FIT
 	imply MULTI_DTB_FIT_USER_DEFINED_AREA