[IA64] trivial cleanup for entry.S

This patch does:
 - make comment at next to resched check more robust
 - move "re-check" comments to next to where change predicate regs

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>