[ATM] firestream: handle thrown error

gcc emits the following warning:

drivers/atm/firestream.c: In function ‘fs_open’:
drivers/atm/firestream.c:870: warning: ‘tmc0’ may be used uninitialized in this function

This indicates a real bug.  We should check make_rate() return value for
potential errors.
Signed-off-by: Jeff Garzik <jeff@garzik.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>

drivers/atm/firestream.c

@@ -1001,6 +1001,10 @@ static int fs_open(struct atm_vcc *atm_vcc)
 					r = ROUND_UP;
 				}
 				error = make_rate (pcr, r, &tmc0, NULL);
+				if (error) {
+					kfree(tc);
+					return error;
+				}
 			}
 			fs_dprintk (FS_DEBUG_OPEN, "pcr = %d.\n", pcr);
 		}