[ATM] firestream: Fix uninitialized var warning.

All code paths set tmc0 in some way, but GCC can't
see that for some reason.  Explicitly initialize
to zero.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/atm/firestream.c b/drivers/atm/firestream.c
index 47c57a4..98099f5 100644
--- a/drivers/atm/firestream.c
+++ b/drivers/atm/firestream.c
@@ -978,6 +978,7 @@
 		/* Docs are vague about this atm_hdr field. By the way, the FS
 		 * chip makes odd errors if lower bits are set.... -- REW */
 		tc->atm_hdr =  (vpi << 20) | (vci << 4); 
+		tmc0 = 0;
 		{
 			int pcr = atm_pcr_goal (txtp);