staging: gasket: remove GASKET_SYSFS_REG()

In an attempt to start to clean up the monstrosity of the sysfs abuse in
the gasket driver, let's remove code that is not used at all.  The
GASKET_SYSFS_REG() macro is never used, so delete it.

Cc: Rob Springer <rspringer@google.com>
Cc: John Joseph <jnjoseph@google.com>
Cc: Ben Chan <benchan@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>