x86/vmx: Rename arch_vmx_struct to vmx_vcpu

x86/vmx: Rename arch_vmx_struct to vmx_vcpu

The suffix and prefix are redundant, and the name is curiously odd.  Rename it
to vmx_vcpu to be consistent with all the other similar structures.  In
addition, rename local arch_vmx local variables to vmx for further
consistency.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---
CC: Roger Pau Monné <roger.pau@citrix.com>
Some of the local pointers are named arch_vmx.  I'm open to renaming them to
just vmx (like all the other local pointers) if people are happy with the
additional patch delta.