KVM: arm64: Refactor kvm_reset_cptr_el2()

Fold kvm_get_reset_cptr_el2() into kvm_reset_cptr_el2(), since it
is its only caller. Add a comment to clarify that this function
is meant for the host value of cptr_el2.

No functional change intended.

Signed-off-by: Fuad Tabba <tabba@google.com>
Link: https://lore.kernel.org/r/20241216105057.579031-14-tabba@google.com


Signed-off-by: Marc Zyngier <maz@kernel.org>