Staging: remove duplicated #include's

Removed duplicated #include's in
  drivers/staging/altpciechdma/altpciechdma.c
  drivers/staging/comedi/comedidev.h
  drivers/staging/rt2860/rt_linux.h
  drivers/staging/rt2870/rt_linux.h

Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>