stm32mp1: add macros to define PLAT_PARTITION_MAX_ENTRIES

There were fixed values when computing PLAT_PARTITION_MAX_ENTRIES.
Use STM32_BL33_PARTS_NUM and STM32_RUNTIME_PARTS_NUM. The first one is
for the number of copies of BL33. The second one depends on the use case
SP_min or OP-TEE. For OP-TEE, there are 3 partitions. For SP_min, as it
is in the same binary as BL2, it is set to 0. It will be set to 1 if
BL32 is in a separate binary.

Change-Id: Iba4d8ec5fbc713bebfbdcd9f9426c3fded20d3ad
Signed-off-by: Yann Gautier <yann.gautier@st.com>

plat/st/stm32mp1/platform.mk

@@ -24,11 +24,15 @@ WORKAROUND_CVE_2017_5715:=	0
 
 # Number of TF-A copies in the device
 STM32_TF_A_COPIES		:=	2
+STM32_BL33_PARTS_NUM		:=	1
 ifeq ($(AARCH32_SP),optee)
-PLAT_PARTITION_MAX_ENTRIES	:=	$(shell echo $$(($(STM32_TF_A_COPIES) + 4)))
+STM32_RUNTIME_PARTS_NUM		:=	3
 else
-PLAT_PARTITION_MAX_ENTRIES	:=	$(shell echo $$(($(STM32_TF_A_COPIES) + 1)))
+STM32_RUNTIME_PARTS_NUM		:=	0
 endif
+PLAT_PARTITION_MAX_ENTRIES	:=	$(shell echo $$(($(STM32_TF_A_COPIES) + \
+							 $(STM32_BL33_PARTS_NUM) + \
+							 $(STM32_RUNTIME_PARTS_NUM))))
 
 # Boot devices
 STM32MP_EMMC		?=	0