i386: Add new Hygon 'Dhyana' CPU model

Add a new base CPU model called 'Dhyana' to model processors from Hygon
Dhyana(family 18h), which derived from AMD EPYC(family 17h).

The following features bits have been removed compare to AMD EPYC:
aes, pclmulqdq, sha_ni

The Hygon Dhyana support to KVM in Linux is already accepted upstream[1].
So add Hygon Dhyana support to Qemu is necessary to create Hygon's own
CPU model.

Reference:
[1] https://git.kernel.org/tip/fec98069fb72fb656304a3e52265e0c2fc9adf87



Signed-off-by: Pu Wen <puwen@hygon.cn>
Message-Id: <1555416373-28690-1-git-send-email-puwen@hygon.cn>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>