This patch change the KSM_REMOVE_MEMORY_REGION ioctl to be specific per
memory region (instead of flushing all the registred memory regions inside
the file descriptor like it happen now)
The previoes api was:
user register memory regions using KSM_REGISTER_MEMORY_REGION inside the fd,
and then when he wanted to remove just one memory region, he had to remove them
all using KSM_REMOVE_MEMORY_REGION.
This patch change this beahivor by chaning the KSM_REMOVE_MEMORY_REGION
ioctl to recive another paramter that it is the begining of the virtual
address that is wanted to be removed.