staging: unisys: move boottotool out of proc to sysfs

Move the proc entry controlling the boottotool flag to procfs. The field
appears in /sys/devices/platform/visorchipset/install/boottotool.

The boottotool flag controls s-Par behavior on the next boot of this guest.
Setting the flag will cause the guest to boot from the utility and installation
image, which will use the value in the toolaction field to determine what
operation is being requested.

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