MLK-20239-3 imx8qm/qxp: Add check for container array index

Fix coverity issue CID 3327493: Negative array index read (NEGATIVE_RETURNS)
negative_returns: Using variable container as an index to array imx_header.fhdr
Signed-off-by: Ye Li <ye.li@nxp.com>

src/imx8qxb0.c

@@ -577,6 +577,10 @@ int build_container_qx_qm_b0(soc_type_t soc, uint32_t sector_size, uint32_t ivt_
 		case SCFW:
 		case DATA:
 		case MSG_BLOCK:
+			if (container < 0) {
+				fprintf(stderr, "No container found\n");
+				exit(EXIT_FAILURE);
+			}
 			check_file(&sbuf, img_sp->filename);
 			tmp_filename = img_sp->filename;
 			set_image_array_entry(&imx_header.fhdr[container],
@@ -594,6 +598,10 @@ int build_container_qx_qm_b0(soc_type_t soc, uint32_t sector_size, uint32_t ivt_
 			break;
 
 		case SECO:
+			if (container < 0) {
+				fprintf(stderr, "No container found\n");
+				exit(EXIT_FAILURE);
+			}
 			check_file(&sbuf, img_sp->filename);
 			tmp_filename = img_sp->filename;
 			set_image_array_entry(&imx_header.fhdr[container],