[missed patch] virttest.utils_misc: Add KSMController class.

@lmr, This is missed KSMController class in utils_misc.
(it seems that you forgot this one when you pushed another patch #1411).
It will not work without this patch, so if nothing error, please merge this one too.

Signed-off-by: Yu Mingfei <yumingfei@cn.fujitsu.com>