This patch configures the TrustZone Controller in Juno to split
the 2GB DDR-DRAM memory at 0x80000000 into Secure and Non-Secure
regions:

- Secure DDR-DRAM: top 16 MB, except for the last 2 MB which are
  used by the SCP for DDR retraining
- Non-Secure DDR-DRAM: remaining DRAM starting at base address

Build option PLAT_TSP_LOCATION selects the location of the secure
payload (BL3-2):

- 'tsram' : Trusted SRAM (default option)
- 'dram'  : Secure region in the DDR-DRAM (set by the TrustZone
            controller)

The MMU memory map has been updated to give BL2 permission to load
BL3-2 into the DDR-DRAM secure region.

Fixes ARM-software/tf-issues#233

Change-Id: I6843fc32ef90aadd3ea6ac4c7f314f8ecbd5d07b