uml: move hppfs_kern.c to hppfs.c

There's no reason for the _kern in hppfs_kern.c, so move it to hppfs.c.

Signed-off-by: Jeff Dike <jdike@linux.intel.com>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>