Revert "KVM: x86: add pcommit support"

Revert "KVM: x86: add pcommit support"

This reverts commit 38241e204d71223e3ee5bf24473107a7d5f94856.

Given the deprecation of the pcommit instruction, the relevant VMX
features and CPUID bits are not going to be rolled into the SDM.  Remove
their usage from KVM.

Cc: Xiao Guangrong <guangrong.xiao@linux.intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>