The private data size is missing from the driver, so we store it at 0,
which causes problems when something overwrites memory at 0.
Fix this.
Change-Id: I6f551ee905b0064ae8343e41e46450c37c8c8c1a
Signed-off-by: Simon Glass <sjg@chromium.org>
Tested-by: Stephen Warren <swarren@wwwdotorg.org>