xen: ia64 build broken due to "xen: switch to new schedop hypercall by default."

The git commit:

> commit a8b74583
> Author: Ian Campbell <ian.campbell@citrix.com>
> Date:   Thu Feb 17 11:04:20 2011 +0000
>
>     xen: switch to new schedop hypercall by default.
>
>     Rename old interface to sched_op_compat and rename sched_op_new to
>     simply sched_op.
>

breaks the IA64 build. This patch fixes it.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Ian Campbell <Ian.Campbell@eu.citrix.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>