rtc: Allow RTC_DRV_CMOS to be used on SPARC.

Add Sparc to the Kconfig depends list.

Add __sparc___ to address_sparc = 128 ifdef.

Finally, don't be concerned about 24-hour BCD mode support if the RTC
doesn't have a valid IRQ.  We won't even use the alarm code in this
case and the Sparc RTCs have this limitation.

Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index 9a9755c..8cb158d 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -329,7 +329,7 @@
 
 config RTC_DRV_CMOS
 	tristate "PC-style 'CMOS'"
-	depends on X86 || ALPHA || ARM || M32R || ATARI || PPC || MIPS
+	depends on X86 || ALPHA || ARM || M32R || ATARI || PPC || MIPS || SPARC
 	default y if X86
 	help
 	  Say "yes" here to get direct support for the real time clock