dm: rtc: Rename mktime() and reduce the number of parameters

Most callers unpack the structure and pass each member. It seems better to
pass the whole structure instead, as with the C library. Also add an rtc_
prefix.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Heiko Schocher <hs@denx.de>
diff --git a/drivers/rtc/imxdi.c b/drivers/rtc/imxdi.c
index e89034d..17519ce 100644
--- a/drivers/rtc/imxdi.c
+++ b/drivers/rtc/imxdi.c
@@ -209,8 +209,7 @@
 			goto err;
 	}
 
-	now = mktime(tmp->tm_year, tmp->tm_mon, tmp->tm_mday,
-		     tmp->tm_hour, tmp->tm_min, tmp->tm_sec);
+	now = rtc_mktime(tmp);
 	/* zero the fractional part first */
 	rc = DI_WRITE_WAIT(0, dtclr);
 	if (rc == 0)