staging: gasket: core: remove sysfs setup and cleanup callbacks

Gasket device drivers now call into the gasket framework to initialize
and de-initialize, rather than the other way around.  The calling code
can perform sysfs setup and cleanup actions without callbacks from the
framework.  Remove the sysfs setup and cleanup callbacks.

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