mm/ksm: Remove reuse_ksm_page()

Remove the function as the last reference has gone away with the do_wp_page()
changes.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Git-commit: 1a0cf26323c80e2f1c58fc04f15686de61bfab0c
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git


Change-Id: Icd11ae747c4b0b9ddd81b8b3c5e463ed88abea9c
Signed-off-by: Zhenhua Huang <zhenhuah@codeaurora.org>