fix(fvp): don't check MPIDRs with the power controller in BL1

The core platform layer requires an implementation for the
`plat_core_pos_by_mpidr` function. This implementation is currently
missing in BL1, which causes undefined reference errors when linking
with LTO.

The FVP platform source file providing this implementation is the
`fvp_topology.c` file, so this change adds it to the BL1 sources for the
FVP.

However, the implementation of this function reaches out to the FVP
power controller driver - `fvp_pm.c` -  to validate the MPIDR, and this
file has at least two other dependencies:

- `spe.c`
- `arm_gicvX.c`

Pulling these in correctly is no simple job, so I am simply removing the
power controller validation in BL1 builds.

Change-Id: I56ddf1d799f5fe7f5b0fb2b046f7fe8232b07b27
Signed-off-by: Chris Kay <chris.kay@arm.com>