userns: On ia64 deal with current_uid and current_gid being kuid and kgid

These ia64 uses of current_uid and current_gid slipped through the
cracks when I was converting everything to kuids and kgids convert
them now.

Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>