Absolute references to kernel source files are generally only useful
locally to the originator of the patch.  Check for any such references and
report them.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>