qemu: Simplify the image size calculation

Patch introduce the macro NS_IMAGE_MAX_SIZE to simplify the image size
calculation. Use of additional parenthesis removes the possibility of
improper calculations due nested macro expansion for subtraction.
In case of platforms with DRAM window over 32bits, patch also removes
potential problems with type casting, as meminfo.image_size is uint32_t
but macro calculations were done in 64bit space.
Signed-off-by: Radoslaw Biernacki <radoslaw.biernacki@linaro.org>
Change-Id: I2d05a2d9dd6000dba6114df53262995cf85af018

plat/qemu/common/qemu_bl2_mem_params_desc.c

 /*
- * Copyright (c) 2017, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -139,8 +139,7 @@ static bl_mem_params_node_t bl2_mem_params_descs[] = {
 	  SET_STATIC_PARAM_HEAD(image_info, PARAM_EP, VERSION_2, image_info_t,
 				0),
 	  .image_info.image_base = NS_IMAGE_OFFSET,
-	  .image_info.image_max_size = NS_DRAM0_BASE + NS_DRAM0_SIZE -
-				       NS_IMAGE_OFFSET,
+	  .image_info.image_max_size = NS_IMAGE_MAX_SIZE,
 # endif /* !PRELOADED_BL33_BASE */
 
 	  .next_handoff_image_id = INVALID_IMAGE_ID,

plat/qemu/qemu/include/platform_def.h

@@ -165,7 +165,8 @@
 # error "Unsupported BL32_RAM_LOCATION_ID value"
 #endif
 
-#define NS_IMAGE_OFFSET			0x60000000
+#define NS_IMAGE_OFFSET			(NS_DRAM0_BASE + 0x20000000)
+#define NS_IMAGE_MAX_SIZE		(NS_DRAM0_SIZE - 0x20000000)
 
 #define PLAT_PHY_ADDR_SPACE_SIZE	(1ULL << 32)
 #define PLAT_VIRT_ADDR_SPACE_SIZE	(1ULL << 32)