arm: rmobile: Add HopeRun HiHope RZ/G2M board support

The HiHope RZ/G2M board from HopeRun consists of main board
(HopeRun HiHope RZ/G2M main board) and sub board(HopeRun
HiHope RZ/G2M sub board). The HiHope RZ/G2M sub board sits
below the HiHope RZ/G2M main board.

This patch adds the required board support to boot HopeRun HiHope
RZ/G2M 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/board/hoperun/hihope-rzg2/MAINTAINERS b/board/hoperun/hihope-rzg2/MAINTAINERS
new file mode 100644
index 0000000..e3702fd
--- /dev/null
+++ b/board/hoperun/hihope-rzg2/MAINTAINERS
@@ -0,0 +1,6 @@
+HIHOPE_RZG2 BOARD
+M:	Biju Das <biju.das.jz@bp.renesas.com>
+S:	Maintained
+F:	board/hoperun/hihope-rzg2/
+F:	include/configs/hihope-rzg2.h
+F:	configs/hihope_rzg2_defconfig