Revert "KVM: SVM: use NPT page attributes"

Revert "KVM: SVM: use NPT page attributes"

This reverts commit d0801bddb31ad1e7c4d2679d5ed098fee628c8cf.
Initializing the mapping from MTRR to PAT values was reported to
fail nondeterministically, and it also caused extremely slow boot
(due to caching getting disabled---bug 103321) with assigned devices.

Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Reported-by: Sebastian Schuette <dracon@ewetel.net>
Cc: stable@vger.kernel.org # 4.2+
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>