Merge changes from topic "stm32mp1_platform_mk" into integration

* changes:
  stm32mp1: cosmetics in platform.mk
  stm32mp1: update rules for stm32image tool
  stm32mp1: add macros to define PLAT_PARTITION_MAX_ENTRIES
  stm32mp1: sort platform.mk
  stm32mp1: use ASFLAGS for binary paths
  stm32mp1: use internal MAKE_LD macro to generate stm32 linker files