board: axs10x - support v3 mother-board

There're 2 versions of motherboards that could be used in ARC SDP.
The only important difference for U-Boot is different NAND IC in use:
 [1] v2 board (we used to support up until now) sports MT29F4G08ABADAWP
while
 [2] v3 board sports MT29F4G16ABADAWP

They are almost the same except data bus width 8-bit in [1] and 16-bit
in [2]. And for proper support of 16-bit data bus we have to pass
NAND_BUSWIDTH_16 option to NAND driver core - which we do now knowing
board type we're running on.

Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
diff --git a/board/synopsys/axs101/axs101.c b/board/synopsys/axs101/axs101.c
index 7742049..8c16410 100644
--- a/board/synopsys/axs101/axs101.c
+++ b/board/synopsys/axs101/axs101.c
@@ -9,6 +9,7 @@
 #include <malloc.h>
 #include <netdev.h>
 #include <phy.h>
+#include "axs10x.h"
 
 DECLARE_GLOBAL_DATA_PTR;
 
@@ -42,3 +43,16 @@
 
 	return 0;
 }
+
+
+#define AXS_MB_CREG	0xE0011000
+
+int board_early_init_f(void)
+{
+	if (readl((void __iomem *)AXS_MB_CREG + 0x234) & (1 << 28))
+		gd->board_type = AXS_MB_V3;
+	else
+		gd->board_type = AXS_MB_V2;
+
+	return 0;
+}