feat(rdfremont): add implementation for GPT setup

Since GPT setup has been delegated to the platform, add an
implementation for plat_bl2_gpt_setup in accordance with the
specification for RD-Fremont variants.

Signed-off-by: Rohit Mathew <rohit.mathew@arm.com>
Change-Id: I1ff47249ce304f1c188850282d92c64cae463383
5 files changed