KVM: arm64: Remove the target table

Finally, remove the target table. Merge the code that checks the
tables into kvm_reset_sys_regs() as there is now only one table.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200622113317.20477-6-james.morse@arm.com