staging: gasket: fix check_and_invoke_callback log param

The message should be passed the callback function pointer, not
the pointer to the gasket device.

Signed-off-by: Zhongze Hu <frankhu@chromium.org>
Signed-off-by: Todd Poynor <toddpoynor@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>