Now that various issues in the PIE support have been fixed,
this platform can enable ENABLE_PIE.

I tested BL2_AT_EL3, BL31, TSP, and all of them worked.

Change-Id: Ibc499c6bad30b7f81a42bfa7e435ce25f820bd9c
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>