x86/paravirt: Move items in pv_info under PARAVIRT_XXL umbrella

All items but name in pv_info are needed by Xen PV only. Define them
with CONFIG_PARAVIRT_XXL set only.

Signed-off-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: xen-devel@lists.xenproject.org
Cc: virtualization@lists.linux-foundation.org
Cc: akataria@vmware.com
Cc: rusty@rustcorp.com.au
Cc: boris.ostrovsky@oracle.com
Cc: hpa@zytor.com
Link: https://lkml.kernel.org/r/20180828074026.820-12-jgross@suse.com