aristainetos: Use imx_ddr_size() for calculating the DDR size

imx_ddr_size() can be used to calculate the DDR size in runtime.

By using this function we no longer need to define PHYS_SDRAM_SIZE.

Cc: Heiko Schocher <hs@denx.de>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Heiko Schocher <hs@denx.de>

board/aristainetos/aristainetos.c

@@ -102,7 +102,7 @@ iomux_v3_cfg_t const usdhc1_pads[] = {
 
 int dram_init(void)
 {
-	gd->ram_size = get_ram_size((void *)PHYS_SDRAM, PHYS_SDRAM_SIZE);
+	gd->ram_size = imx_ddr_size();
 
 	return 0;
 }