rtc: m41t62: add compatible for m41st87

This adds a compatible string for m41st87. This ensures that this driver
can be used for m41st87.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Simon Goldschmidt <simon.k.r.goldschmidt@gmail.com>
Cc: Stefan Roese <sr@denx.de>
Reviewed-by: Stefan Roese <sr@denx.de>

drivers/rtc/m41t62.c

@@ -173,6 +173,7 @@ static const struct rtc_ops m41t62_rtc_ops = {
 static const struct udevice_id m41t62_rtc_ids[] = {
 	{ .compatible = "st,m41t62" },
 	{ .compatible = "st,m41t82" },
+	{ .compatible = "st,m41st87" },
 	{ .compatible = "microcrystal,rv4162" },
 	{ }
 };