KVM: arm64: Compile remaining hyp/ files for both VHE/nVHE

The following files in hyp/ contain only code shared by VHE/nVHE:
  vgic-v3-sr.c, aarch32.c, vgic-v2-cpuif-proxy.c, entry.S, fpsimd.S
Compile them under both configurations. Deletions in image-vars.h reflect
eliminated dependencies of nVHE code on the rest of the kernel.

Signed-off-by: David Brazdil <dbrazdil@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200625131420.71444-14-dbrazdil@google.com