include/linux/xz.h: drop duplicated word

Drop the doubled word "than" in a comment.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Lasse Collin <lasse.collin@tukaani.org>
Link: http://lkml.kernel.org/r/05ebba7a-c1e4-01ae-fc7b-15c081b33f3e@infradead.org


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>