hw/rdma: Use correct print format in CHK_ATTR macro

hw/rdma: Use correct print format in CHK_ATTR macro

Macro should not cast the given variable to u64 instead it should use
the supplied format argument (fmt).

Reported-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20180322095220.9976-3-yuval.shaia@oracle.com>
Signed-off-by: Marcel Apfelbaum <marcel@redhat.com>