mISDN: Support DR6 indication in mISDNipac driver

According to figure 39 in PEB3086 data sheet, version 1.4 this indication
replaces DR when layer 1 transition source state is F6.

This fixes mISDN layer 1 getting stuck in F6 state in TE mode on
Dialogic Diva 2.02 card (and possibly others) when NT deactivates it.
Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Acked-by: Karsten Keil <keil@b1-systems.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/isdn/hardware/mISDN/ipac.h

@@ -217,6 +217,7 @@ struct ipac_hw {
 #define ISAC_IND_SD		0x2
 #define ISAC_IND_DIS		0x3
 #define ISAC_IND_RSY		0x4
+#define ISAC_IND_DR6		0x5
 #define ISAC_IND_EI		0x6
 #define ISAC_IND_PU		0x7
 #define ISAC_IND_ARD		0x8

drivers/isdn/hardware/mISDN/mISDNipac.c

@@ -80,6 +80,7 @@ isac_ph_state_bh(struct dchannel *dch)
 		l1_event(dch->l1, HW_DEACT_CNF);
 		break;
 	case ISAC_IND_DR:
+	case ISAC_IND_DR6:
 		dch->state = 3;
 		l1_event(dch->l1, HW_DEACT_IND);
 		break;
@@ -660,6 +661,7 @@ isac_l1cmd(struct dchannel *dch, u32 cmd)
 		spin_lock_irqsave(isac->hwlock, flags);
 		if ((isac->state == ISAC_IND_EI) ||
 		    (isac->state == ISAC_IND_DR) ||
+		    (isac->state == ISAC_IND_DR6) ||
 		    (isac->state == ISAC_IND_RS))
 			ph_command(isac, ISAC_CMD_TIM);
 		else