boards: fvp_baser_aemv8r: remove SOC_FVP_AEMV8R_EL2_INIT code

Now that VMPIDR_EL2 will be initialized in z_arm64_el2_init, the code
that I wrote for initializing VMPIDR_EL2 on fvp_baser_aemv8r can be
removed.

Signed-off-by: Huifeng Zhang <Huifeng.Zhang@arm.com>