[PATCH] ia64: desc_empty thinko/typo fix

Just a one-byter for an ia64 thinko/typo - already fixed for i386 and x86_64.

Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>