fix(st): fix NULL pointer dereference issues

The get_bl_mem_params_node() function could return NULL. Add asserts to
check the return value is not NULL.
This corrects coverity issues:
	pager_mem_params = get_bl_mem_params_node(BL32_EXTRA1_IMAGE_ID);
>>>     CID 378360:    (NULL_RETURNS)
>>>     Dereferencing "pager_mem_params", which is known to be "NULL".

	paged_mem_params = get_bl_mem_params_node(BL32_EXTRA2_IMAGE_ID);
>>>     CID 378360:    (NULL_RETURNS)
>>>     Dereferencing "paged_mem_params", which is known to be "NULL".

	tos_fw_mem_params = get_bl_mem_params_node(TOS_FW_CONFIG_ID);
>>>     CID 378360:    (NULL_RETURNS)
>>>     Dereferencing "tos_fw_mem_params", which is known to be "NULL".


Do the same for other occurrences of get_bl_mem_params_node() return not
checked, in the functions plat_get_bl_image_load_info() and
bl2_plat_handle_pre_image_load().

Signed-off-by: Yann Gautier <yann.gautier@st.com>
Change-Id: I79165b1628fcee3da330f2db4ee5e1dafcb1b21f
diff --git a/plat/st/stm32mp1/bl2_plat_setup.c b/plat/st/stm32mp1/bl2_plat_setup.c
index 0d554bd..6f5fcc7 100644
--- a/plat/st/stm32mp1/bl2_plat_setup.c
+++ b/plat/st/stm32mp1/bl2_plat_setup.c
@@ -463,12 +463,14 @@
 
 				/* In case of OPTEE, initialize address space with tos_fw addr */
 				pager_mem_params = get_bl_mem_params_node(BL32_EXTRA1_IMAGE_ID);
+				assert(pager_mem_params != NULL);
 				pager_mem_params->image_info.image_base = config_info->config_addr;
 				pager_mem_params->image_info.image_max_size =
 					config_info->config_max_size;
 
 				/* Init base and size for pager if exist */
 				paged_mem_params = get_bl_mem_params_node(BL32_EXTRA2_IMAGE_ID);
+				assert(paged_mem_params != NULL);
 				paged_mem_params->image_info.image_base = STM32MP_DDR_BASE +
 					(dt_get_ddr_size() - STM32MP_DDR_S_SIZE -
 					 STM32MP_DDR_SHMEM_SIZE);
@@ -526,6 +528,7 @@
 #if !STM32MP_USE_STM32IMAGE
 			bl_mem_params->ep_info.pc = bl_mem_params->image_info.image_base;
 			tos_fw_mem_params = get_bl_mem_params_node(TOS_FW_CONFIG_ID);
+			assert(tos_fw_mem_params != NULL);
 			bl_mem_params->image_info.image_max_size +=
 				tos_fw_mem_params->image_info.image_max_size;
 #endif /* !STM32MP_USE_STM32IMAGE */