[IA64] sprintf should not be used with same source & destination address

This happens to work at the moment but isn't a good idea so fix it the
simple way.

Resolves-bug: http://bugzilla.kernel.org/show_bug.cgi?id=13576



Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>