um: Remove hppfs

hppfs (honeypot procfs) was an attempt to use UML as honeypot.
It was never stable nor in heavy use.

As Al Viro and Christoph Hellwig pointed some major issues out
it is better to let it die.

Signed-off-by: Richard Weinberger <richard@nod.at>

diff --cc arch/um/Kconfig.um
Simple merge

diff --cc fs/Makefile
Simple merge

diff --cc fs/hppfs/Makefile
Simple merge

diff --cc fs/hppfs/hppfs.c
Simple merge