Fix gcc warnings

• Put parentheses around bitwise OR'ed values in the FIELD_COPY(..) and FIELD_REPLACE(..) macros to mute warning from gcc 4.2.1.
• Remove -Wunused-but-set-variable's (setup_addr, status_addr).

Approved by: re (gjb)
Differential Revision: https://reviews.freebsd.org/D7119
MFC after: 1 week
X-MFC with: r302332
Reported by: Jenkins
Reviewed by: grehan (maintainer)
Sponsored by: EMC / Isilon Storage Division