rtc: add support for 4543 RTC (manufactured by e.g. EPSON)

Signed-off-by: Detlev Zundel <dzu@denx.de>
Signed-off-by: Andreas Pfefferle <ap@denx.de>
diff --git a/include/rtc.h b/include/rtc.h
index 785fbe3..019c2eb 100644
--- a/include/rtc.h
+++ b/include/rtc.h
@@ -61,4 +61,8 @@
 unsigned long mktime (unsigned int, unsigned int, unsigned int,
 		      unsigned int, unsigned int, unsigned int);
 
+uchar rtc_read(uchar reg) __attribute__((weak));
+void  rtc_write(uchar reg, uchar val) __attribute__((weak));
+
+
 #endif	/* _RTC_H_ */