feat(fvp): enable errata management interface

feat(fvp): enable errata management interface

Errata ABI feature specific build flag, flag to enable
CPUs in the cpu list, flags to test non-arm interconnect based
errata flags when enabled from a platform level.
Added to the FVP platform makefile to test the errata abi feature
implementation.

The flags to enable CPUs in the cpu list will be removed once
synchronized with the errata framework.

Change-Id: I30877a22ac1348906a6ddfb26f9e8839912d3572
Signed-off-by: Sona Mathew <SonaRebecca.Mathew@arm.com>