RDMA/usnic: Make the compiler check declaration consistency during compilation

This patch avoids that sparse complains about missing declarations.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christian Benvenuti <benve@cisco.com>
Cc: Dave Goodell <dgoodell@cisco.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>