cxgb4: smt: Use normal int for refcount

All refcount operations are protected by spinlocks now.
Then the atomic counter can be replaced by a normal int.

This patch depends on PATCH 1/2.

Signed-off-by: Chuhong Yuan <hslester96@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>