HID: lg: make transfer buffers DMA capable

Kernel v4.9 strictly enforces DMA capable buffers, so we need to remove
buffers allocated on the stack.

[jkosina@suse.cz: fix up second usage of hid_hw_raw_request(), spotted by
 0day build bot]
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>