Add a Kconfig option to allow people who don't want cross memory attach to
not have it included in their build.
Signed-off-by: NChris Yeoh <yeohc@au1.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>