tools: imx8image: Fix potential memory leak

Dynamic memory, referenced by 'line', is allocated at imx8image.c:270
by calling function 'getline' and lost at imx8image.c:294.

Signed-off-by: Maks Mishin <maks.mishinFZ@gmail.com>

tools/imx8image.c

@@ -290,6 +290,7 @@ static uint32_t parse_cfg_file(image_t *param_stack, char *name)
 		}
 	}
 
+	free(line);
 	fclose(fd);
 	return 0;
 }