Revert "x86/hvm: add support for pcommit instruction"

Revert "x86/hvm: add support for pcommit instruction"

This reverts commit cfacce340608be5f94ce0c8f424487b63c3d5399.

Platforms supporting Intel NVDIMM are now required to provide
persistency once pmem stores are accepted by the memory subsystem.
This is usually achieved by a platform-level feature known as ADR
(Asynchronous DRAM Refresh) that flushes any memory subsystem write
pending queues on power loss/shutdown. Therefore, the pcommit
instruction, which has not yet shipped on any product (and will not),
is no longer needed and is deprecated.

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>