am33xx, davinci: Create and use <asm/davinci_rtc.h>

Create a common header file for the RTC IP block that is shared between
davinci and am33xx.

Signed-off-by: Tom Rini <trini@ti.com>
diff --git a/drivers/rtc/davinci.c b/drivers/rtc/davinci.c
index 018779e..f862e2f 100644
--- a/drivers/rtc/davinci.c
+++ b/drivers/rtc/davinci.c
@@ -8,7 +8,7 @@
 #include <command.h>
 #include <rtc.h>
 #include <asm/io.h>
-#include <asm/arch/hardware.h>
+#include <asm/davinci_rtc.h>
 
 #if defined(CONFIG_CMD_DATE)
 int rtc_get(struct rtc_time *tmp)