board: toradex: verdin-imx8mm: increase maximum addressable ram to 4GB

Add support for SKUs with higher memory sizes.
Actual memory size is auto-detected.

Signed-off-by: Emanuele Ghidoli <emanuele.ghidoli@toradex.com>
diff --git a/include/configs/verdin-imx8mm.h b/include/configs/verdin-imx8mm.h
index 34238d3..12d2b68 100644
--- a/include/configs/verdin-imx8mm.h
+++ b/include/configs/verdin-imx8mm.h
@@ -58,8 +58,10 @@
 #define CFG_SYS_SDRAM_BASE           0x40000000
 
 /* SDRAM configuration */
-#define PHYS_SDRAM                      0x40000000
-#define PHYS_SDRAM_SIZE			SZ_2G /* 2GB DDR */
+#define PHYS_SDRAM                   0x40000000
+#define PHYS_SDRAM_SIZE              (long)(SZ_2G + SZ_1G)
+#define PHYS_SDRAM_2                 0x100000000
+#define PHYS_SDRAM_2_SIZE            (long)(SZ_1G)
 
 /* USB Configs */
 #define CFG_MXC_USB_PORTSC	(PORT_PTS_UTMI | PORT_PTS_PTW)