ipw2200: Check for -1 INTA in tasklet too.

This is an attempt to fix a long standing open bug:
http://bugzilla.intellinuxwireless.org/show_bug.cgi?id=1334

The interrupt handler checks for INTA being -1, apparently that means that the
hardware is gone. But the interrupt handler defers actual interrupt processing
to a tasklet. By the time the tasklet is run and checks INTA again, the
hardware might be gone and INTA be -1, which confuses the driver because all
event bits are set.

The patch applies to 2.6.37.
Signed-off-by: Indan Zupancic <indan@nul.nu>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ipw2x00/ipw2200.c

@@ -1973,6 +1973,13 @@ static void ipw_irq_tasklet(struct ipw_priv *priv)
 
 	inta = ipw_read32(priv, IPW_INTA_RW);
 	inta_mask = ipw_read32(priv, IPW_INTA_MASK_R);
+
+	if (inta == 0xFFFFFFFF) {
+		/* Hardware disappeared */
+		IPW_WARNING("TASKLET INTA == 0xFFFFFFFF\n");
+		/* Only handle the cached INTA values */
+		inta = 0;
+	}
 	inta &= (IPW_INTA_MASK_ALL & inta_mask);
 
 	/* Add any cached INTA values that need to be handled */