staging: gasket: always allow root open for write

Always allow root to open device for writing.

Drop special-casing of ioctl permissions for root vs. owner.

Convert to bool types as appropriate.

Reported-by: Dmitry Torokhov <dtor@chromium.org>
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>