fix: cactus entry point get core linear id

In the cactus entry point there is remnant call to the platform specific
physical MPIDR to linear id conversion routine. This is incorrect
because S-EL1 read of MPIDR is emulated by the SPMC and returns the vCPU
linear id rather than the physical MPIDR.

Add a check that the core linear id inferred by MPIDR is matching the id
passed by the SPMC through x4. This feature was added to support legacy
TEEs expecting the core linear id to be passed by TF-A.

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Change-Id: I6902e8f06ab6c79953f6891e582fc8975825a6c4