mm: Export symbol ksize()

Commit 7b2cd92adc5430b0c1adeb120971852b4ea1ab08 ("crypto: api - Fix
zeroing on free") added modular user of ksize(). Export that to fix
crypto.ko compilation.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>

diff --cc mm/slab.c
Simple merge

diff --cc mm/slob.c
Simple merge

diff --cc mm/slub.c
Simple merge