[ATM] drivers/atm/iphase.c: compilation warning fix

Removed the warning messages:
drivers/atm/iphase.c:961: warning: 'tcnter' defined but not used
drivers/atm/iphase.c:963: warning: 'xdump' defined but not used

tcnter and xdump() are used only in debug build

Signed-off-by: Leonardo Potenza <lpotenza@inwind.it>
Signed-off-by: David S. Miller <davem@davemloft.net>