ARM: keystone2: use detected ddr3a size

Because KS2 u-boot works in 32 bit address space the existing ram_size
global data field cannot be used. The maximum, which the get_ram_size()
can detect is 2GB only. The ft_board_setup() needs the actual ddr3 size
to fix up dtb.

This commit introduces the ddr3_get_size() which uses SPD data to
calculate the ddr3 size. This function replaces the "ddr3_size"
environment variable, which was used to get the SODIMM size.

For platforms, which don't have SODIMM with SPD and ddr3 is populated to
a board a simple ddr3_get_size function that returns ddr3 size has to be
implemented. See hardware-k2l.h

Signed-off-by: Vitaly Andrianov <vitalya@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
diff --git a/arch/arm/mach-keystone/ddr3_spd.c b/arch/arm/mach-keystone/ddr3_spd.c
index e5018c9..c541886 100644
--- a/arch/arm/mach-keystone/ddr3_spd.c
+++ b/arch/arm/mach-keystone/ddr3_spd.c
@@ -426,6 +426,16 @@
 	return 0;
 }
 
+int ddr3_get_size(void)
+{
+	ddr3_spd_eeprom_t spd_params;
+
+	if (ddr3_read_spd(&spd_params))
+		return 0;
+
+	return ddr3_get_size_in_mb(&spd_params) / 1024;
+}
+
 int ddr3_get_dimm_params_from_spd(struct ddr3_spd_cb *spd_cb)
 {
 	struct ddr3_sodimm spd;