arm/mach-integrator/time.c, mwave: revert portions of recent irq cleanups

The recent irq cleanups for arch/arm/mach-integrator/time.c and
drivers/char/mwave/tp3780i.c changed the request_irq() dev_id
parameter, but neglected to change the matching free_irq() parameter,
thus creating a bug upon irq de-registration.

Given that the impetus for the changes is not yet accepted upstream,
it is best to revert the irq cleanups.

Mostly.  A comment is added to time.c to reduce future confusion,
of type that led to my time.c cleanup in the first place.

Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/arch/arm/mach-integrator/time.c b/arch/arm/mach-integrator/time.c
index 5235f64..8508a0d 100644
--- a/arch/arm/mach-integrator/time.c
+++ b/arch/arm/mach-integrator/time.c
@@ -124,8 +124,11 @@
 
 	xtime.tv_sec = __raw_readl(rtc_base + RTC_DR);
 
+	/* note that 'dev' is merely used for irq disambiguation;
+	 * it is not actually referenced in the irq handler
+	 */
 	ret = request_irq(dev->irq[0], arm_rtc_interrupt, IRQF_DISABLED,
-			  "rtc-pl030", NULL);
+			  "rtc-pl030", dev);
 	if (ret)
 		goto map_out;