sh: disable genrtc support.

sh never had support for this, so remove the option entirely.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

drivers/char/Kconfig

@@ -815,7 +815,7 @@ config SGI_IP27_RTC
 
 config GEN_RTC
 	tristate "Generic /dev/rtc emulation"
-	depends on RTC!=y && !IA64 && !ARM && !M32R && !SPARC && !FRV && !S390
+	depends on RTC!=y && !IA64 && !ARM && !M32R && !SPARC && !FRV && !S390 && !SUPERH
 	---help---
 	  If you say Y here and create a character special file /dev/rtc with
 	  major number 10 and minor number 135 using mknod ("man mknod"), you