colibri_imx7: prime get_ram_size() using imx_ddr_size()

Rather than passing a hardcoded maxsize to the generic get_ram_size()
function use the i.MX 7 specific imx_ddr_size() function, which extracts
the memory size at runtime by reading the DDR controller registers.

This is a purely cosmetic change as the generic get_ram_size() function
already took care of properly automatically detecting 256MB, 512MB or 1GB
modules.
Signed-off-by: NFabio Estevam <festevam@gmail.com>
Signed-off-by: NMarcel Ziswiler <marcel.ziswiler@toradex.com>
Reviewed-by: NFabio Estevam <fabio.estevam@nxp.com>
Acked-by: NStefan Agner <stefan.agner@toradex.com>

board/toradex/colibri_imx7/colibri_imx7.c

@@ -52,7 +52,7 @@ DECLARE_GLOBAL_DATA_PTR;
 
 int dram_init(void)
 {
-	gd->ram_size = get_ram_size((void *)PHYS_SDRAM, PHYS_SDRAM_SIZE);
+	gd->ram_size = get_ram_size((void *)PHYS_SDRAM, imx_ddr_size());
 
 	return 0;
 }

include/configs/colibri_imx7.h

@@ -14,7 +14,6 @@
 #include "mx7_common.h"
 
 /*#define CONFIG_DBG_MONITOR*/
-#define PHYS_SDRAM_SIZE			SZ_1G
 
 /* Size of malloc() pool */
 #define CONFIG_SYS_MALLOC_LEN		(32 * SZ_1M)