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/board/enbw/enbw_cmc/enbw_cmc.c b/board/enbw/enbw_cmc/enbw_cmc.c
index c477962..39efe20 100644
--- a/board/enbw/enbw_cmc/enbw_cmc.c
+++ b/board/enbw/enbw_cmc/enbw_cmc.c
@@ -36,6 +36,7 @@
 #include <asm/arch/hardware.h>
 #include <asm/arch/sdmmc_defs.h>
 #include <asm/arch/timer_defs.h>
+#include <asm/davinci_rtc.h>
 
 DECLARE_GLOBAL_DATA_PTR;