hw/arm/imx25_pdk: Fix error message for invalid RAM size

The i.MX25 PDK board has 2 banks for SDRAM, each can
address up to 256 MiB. So the total RAM usable for this
board is 512M. When we ask for more we get a misleading
error message:

  $ qemu-system-arm -M imx25-pdk -m 513M
  qemu-system-arm: Invalid RAM size, should be 128 MiB

Update the error message to better match the reality:

  $ qemu-system-arm -M imx25-pdk -m 513M
  qemu-system-arm: RAM size more than 512 MiB is not supported

Fixes: bf350daa ("arm/imx25_pdk: drop RAM size fixup")
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Message-id: 20210407225608.1882855-1-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

hw/arm/imx25_pdk.c

@@ -65,7 +65,6 @@ static struct arm_boot_info imx25_pdk_binfo;
 
 static void imx25_pdk_init(MachineState *machine)
 {
-    MachineClass *mc = MACHINE_GET_CLASS(machine);
     IMX25PDK *s = g_new0(IMX25PDK, 1);
     unsigned int ram_size;
     unsigned int alias_offset;
@@ -77,8 +76,8 @@ static void imx25_pdk_init(MachineState *machine)
 
     /* We need to initialize our memory */
     if (machine->ram_size > (FSL_IMX25_SDRAM0_SIZE + FSL_IMX25_SDRAM1_SIZE)) {
-        char *sz = size_to_str(mc->default_ram_size);
-        error_report("Invalid RAM size, should be %s", sz);
+        char *sz = size_to_str(FSL_IMX25_SDRAM0_SIZE + FSL_IMX25_SDRAM1_SIZE);
+        error_report("RAM size more than %s is not supported", sz);
         g_free(sz);
         exit(EXIT_FAILURE);
     }