Merge changes from topic "pie" into integration

* changes:
  uniphier: make all BL images completely position-independent
  uniphier: make uniphier_mmap_setup() work with PIE
  uniphier: pass SCP base address as a function parameter
  uniphier: set buffer offset and length for io_block dynamically
  uniphier: use more mmap_add_dynamic_region() for loading images
  bl_common: add BL_END macro
  uniphier: turn on ENABLE_PIE
  TSP: add PIE support
  BL2_AT_EL3: add PIE support
  BL31: discard .dynsym .dynstr .hash sections to make ENABLE_PIE work
  PIE: pass PIE options only to BL31
  Build: support per-BL LDFLAGS