Documentation: update GregKH links

Fixed the broken links in the SubmittingPatches file.

[ The old links turn out to not be broken after all, but the new links
  are certainly more readable - Linus ]

Signed-off-by: Vikram Narayanan <vikram186@gmail.com>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>