HID: picoLCD: fix dumping of IR_DATA report

The first payload byte indicates how many IR data bytes are following, not
including itself. The IR data bytes appear in pairs as they represent a
series of 16bit intervals.

Signed-off-by: Bruno Prémont <bonbons@linux-vserver.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>