hpfs: add fstrim support

This patch adds support for fstrim to the HPFS filesystem.

Signed-off-by: Mikulas Patocka <mikulas@twibright.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --cc fs/hpfs/alloc.c
Simple merge

diff --cc fs/hpfs/dir.c
Simple merge

diff --cc fs/hpfs/file.c
Simple merge

diff --cc fs/hpfs/hpfs_fn.h
Simple merge

diff --cc fs/hpfs/super.c
Simple merge