HID: battery: don't do DMA from stack

Instead of using data from stack for DMA in hidinput_get_battery_property(),
allocate the buffer dynamically.

Cc: stable@kernel.org
Reported-by: Richard Ryniker <ryniker@alum.mit.edu>
Reported-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>