selftests/vm: ksm_functional_tests: fix a typo in comment

Fix a typo of "comaring" which should be "comparing".

Link: https://lkml.kernel.org/r/202212231050245952617@zte.com.cn


Signed-off-by: Xu Panda <xu.panda@zte.com.cn>
Signed-off-by: xu xin <xu.xin16@zte.com.cn>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>