card_emu: Fix computation of waiting time

As we store the waiting time (WT) in 'etu', we must adjust the formula
from ISO 7816-3.  The 'Fi' component in the formula only exists to
compute clock cycles from the etu, which we don't need here.

Without this patch, the waiting time would be way too large (by a factor
of 372 in the default case).

Change-Id: Ia21bc7303f9b38834b5b1753983ed2a99bfc7d95

firmware/libcommon/source/card_emu.c

@@ -505,8 +505,11 @@ static int tx_byte_atr(struct card_handle *ch)
 				}
 			}
 		}
-		/* update waiting time (see ISO 7816-3 10.2) */
-		ch->waiting_time = ch->wi * 960 * iso7816_3_fi_table[ch->F_index];
+		/* update waiting time (see ISO 7816-3 10.2). We can drop the Fi
+		 * multiplier as we store the waiting time in units of 'etu', and
+		 * don't really care what the number of clock cycles or the absolute
+		 * wall clock time is */
+		ch->waiting_time = ch->wi * 960;
 		/* go to next state */
 		card_set_state(ch, ISO_S_WAIT_TPDU);
 		return 0;

firmware/libcommon/source/mode_cardemu.c

@@ -225,7 +225,6 @@ static uint16_t compute_next_timeout(struct cardem_inst *ci)
 		want_to_expire = ci->wt.remaining - (ci->wt.total / 2);
 	} else
 		want_to_expire = ci->wt.remaining;
-	TRACE_INFO("want_to_expire=%u (total=%u, remaining=%u)\r\n", want_to_expire, ci->wt.total, ci->wt.remaining);
 	/* if value exceeds the USART TO range, use the maximum possible value for one round */
 	return OSMO_MIN(want_to_expire, 0xffff);
 }