Revert "KVM: MMU: record maximum physical address width in kvm_mmu_extended_role"

Drop MAXPHYADDR from mmu_role now that all MMUs have their role
invalidated after a CPUID update.  Invalidating the role forces all MMUs
to re-evaluate the guest's MAXPHYADDR, and the guest's MAXPHYADDR can
only be changed only through a CPUID update.

This reverts commit de3ccd26.

Cc: Yu Zhang <yu.c.zhang@linux.intel.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20210622175739.3610207-9-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>