RDMA/cxgb3: Timeout condition is never true

This is a static checker fix.  "count" is unsigned so it's never -1.
Since "count" is 16 bits and the addition operation is implicitly
casted to int then there is no wrapping here.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>