staging: gasket: core: let device driver enable/disable gasket device

Move gasket device enable/disable functions from internal calls to
external calls from the gasket device drivers.  The device driver will
call these functions at appropriate times in its processing, placing
the device driver in control of this sequence and reducing the need for
callbacks from framework back to the device drivers during the
enable/disable sequences.

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