There is no reason for generic hid-input.c to include usb-specific
input.h.

As a sideeffect, this also fixes warning of redefinition of dbg()
macro, when hid-input.c is compiled with DEBUG (as there is a clash
between dbg() from hid.h and usb/input.h).
Signed-off-by: Jiri Kosina <jkosina@suse.cz>