xen/balloon: Move the registration from device to subsystem.

With git commit 070680218379e15c1901f4bf21b98e3cbf12b527
"xen-balloon: convert sysdev_class to a regular subsystem" we would
end up with the attributes being put in:

 /sys/devices/xen_memory0/target_kb
instead of
/sys/devices/system/xen_memory/xen_memory0/target_kb

Making the tools inable to deflate the kernel to make more space
for launching another guest and printing:
Error: Failed to query current memory allocation of dom0

Reported-by: Sander Eikelenboom <[email protected]>
Suggested-by:  Kay Sievers <[email protected]>
Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>

0 files changed, 0 insertions, 0 deletions