MAINTAINERS: change hugetlbfs maintainer and update files

The current hugetlbfs maintainer has not been active for more than a few
years.  I have been been active in this area for more than two years and
plan to remain active in the foreseeable future.

Also, update the hugetlbfs entry to include linux-mm mail list and
additional hugetlbfs related files.  hugetlb.c and hugetlb.h are not
100% hugetlbfs, but a majority of their content is hugetlbfs related.

Link: http://lkml.kernel.org/r/20180518225236.19079-1-mike.kravetz@oracle.com
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Nadia Yvette Chambers <nyc@holomorphy.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>