staging: unisys: move chipsetready to sysfs

Move the chipsetready proc entry to sysfs under a new directory guest. This
entry is used by Unisys application software on the guest to acknowledge
completion of specific events for integration purposes, but these
acknowledgements are not required for the guest to operate correctly.

The store function is simplified as well, to use scanf() instead of copying
the buffer and using strsep().

Signed-off-by: Benjamin Romer <benjamin.romer@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>