staging: gasket: page_table: rearrange gasket_page_table_entry

Rearrange gasket_page_table entry to reduce padding slop.

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