fix(nxp/common/setup): fix total dram size checking

total_dram_size should be signed value because it is equal to return
value of init_ddr(), so if it is lower or equal zero, report
error as DDR is not initialized correctly.

Signed-off-by: Jiafei Pan <Jiafei.Pan@nxp.com>
Change-Id: Idbc40da103f60f10cb18c5306e97b764c1a9d372
diff --git a/plat/nxp/common/setup/ls_bl2_el3_setup.c b/plat/nxp/common/setup/ls_bl2_el3_setup.c
index 6428eb9..5b5144d 100644
--- a/plat/nxp/common/setup/ls_bl2_el3_setup.c
+++ b/plat/nxp/common/setup/ls_bl2_el3_setup.c
@@ -279,10 +279,12 @@
 
 	soc_preload_setup();
 
-	if (dram_regions_info.total_dram_size < NXP_DRAM0_SIZE) {
-		NOTICE("ERROR: DRAM0 Size is not correctly configured.");
+#ifdef DDR_INIT
+	if (dram_regions_info.total_dram_size <= 0) {
+		ERROR("Asserting as the DDR is not initialized yet.");
 		assert(false);
 	}
+#endif
 
 	if ((dram_regions_info.region[0].addr == 0)
 		&& (dram_regions_info.total_dram_size > 0)) {