[IA64] Update to use account_{steal,idle}_ticks

This patch fixes the following errors caused by
79741dd3 which changed
the prototypes of account_steal_time() and account_idle_time().

>   CC      arch/ia64/xen/time.o
> arch/ia64/xen/time.c: In function 'consider_steal_time':
> arch/ia64/xen/time.c:132: warning: passing argument 1 of 'account_steal_time' makes integer from pointer without a cast
> arch/ia64/xen/time.c:132: error: too many arguments to function 'account_steal_time'
> arch/ia64/xen/time.c:133: warning: passing argument 1 of 'account_steal_time' makes integer from pointer without a cast
> arch/ia64/xen/time.c:133: error: too many arguments to function 'account_steal_time'

Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
Signed-off-by: Tony Luck <tony.luck@intel.com>