staging: comedi: shrink comedi_compat32.h

staging: comedi: shrink comedi_compat32.h

"comedi_compat32.h" #include's <linux/compat.h>, but that is only needed
by "comedi_compat32.c" so move the #include to that file.  Also,
"comedi_compat.h" doesn't really need the '#include <linux/fs.h>' just
to declare 'struct file' as it only uses it to construct a pointer to
that type.  Replace that #include with an incomplete declaration of
'struct file' and move that #include into "comedi_compat32.c".

Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>