They've been introduced by 987a6c02 ("Input: switch to input_abs_*()
access functions") and they appear to be some kind of debug left-over.

[Dmitry Torokhov: these are my fault - I added XX prefixes in places where
 I wanted to do additional review of the code but failed to actually do
 that in these particular instances.]
Signed-off-by: Daniel Mack <daniel@caiaq.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>