lguest: remove NOTIFY call and eventfd facility.

Disappointing, as this was kind of neat (especially getting to use RCU
to manage the address -> eventfd mapping).  But now the devices are PCI
handled in userspace, we get rid of both the NOTIFY hypercall and
the interface to connect an eventfd.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --cc arch/x86/include/asm/lguest_hcall.h
Simple merge

diff --cc drivers/lguest/core.c
Simple merge

diff --cc drivers/lguest/hypercalls.c
Simple merge

diff --cc drivers/lguest/lg.h
Simple merge

diff --cc drivers/lguest/lguest_user.c
Simple merge

diff --cc include/linux/lguest_launcher.h
Simple merge