sparc: Fix multiple RTC detections on SUN4D

Sorry about the slow response. Had some memory issues with the
testbox.

On SUN4D machines there is one RTC-chip located on each systemboard,
when
booting all of these will be probed. Registering a second RTC with the
kernel fails, and breaks the rtc:
[ 0.212000] kobject (f02625f0): tried to init an initialized object,
somethi
[ 0.212000] [f0141418 : platform_device_register+0x4/0x18 ] [f01edbc4
: cloc
[    0.216000] ------------[ cut here ]------------
[ 0.216000] WARNING: at fs/sysfs/dir.c:487 sysfs_add_one+0x84/0xa4()
[ 0.216000] sysfs: cannot create duplicate filename
'/devices/platform/rtc-m
[    0.216000] Modules linked in:
[ 0.216000] [f00c1988 : sysfs_add_one+0x84/0xa4 ] [f00c1f70 :
create_dir+0x4
[    0.216000] ---[ end trace 139ce121c98e96c9 ]---
[ 0.220000] kobject_add_internal failed for rtc-m48t59.0 with -EEXIST,
don't
[ 0.220000] [f013d568 : device_add+0xc8/0x610 ] [f014134c :
platform_device_
[    0.220000] Registering RTC device failed

Later on in the boot the following happens:
[   23.116000] drivers/rtc/hctosys.c: unable to open rtc device (rtc0)

The suggested fix searches the supplied RTC node for a address
property
which only one RTC per system appears to have and registers only this
RTC
with the kernel. (Tested on SS20/SUN4M and SS1000E/SUN4D).
Signed-off-by: Kjetil Oftedal <oftedal@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/time_32.c

@@ -156,6 +156,10 @@ static int __devinit clock_probe(struct of_device *op, const struct of_device_id
 	if (!model)
 		return -ENODEV;
 
+	/* Only the primary RTC has an address property */
+	if (!of_find_property(dp, "address", NULL))
+		return -ENODEV;
+
 	m48t59_rtc.resource = &op->resource[0];
 	if (!strcmp(model, "mk48t02")) {
 		/* Map the clock register io area read-only */