rtc: ds1307: Add bindings for microchip, mcp7940x

Compatible string microchip,mcp7940x is used by Turris Mox DTS file in
Linux kernel and U-Boot ds1307.c driver works fine with it.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/drivers/rtc/ds1307.c b/drivers/rtc/ds1307.c
index 1963565..40ca66b 100644
--- a/drivers/rtc/ds1307.c
+++ b/drivers/rtc/ds1307.c
@@ -358,6 +358,7 @@
 	{ .compatible = "dallas,ds1337", .data = ds_1337 },
 	{ .compatible = "dallas,ds1339", .data = ds_1339 },
 	{ .compatible = "dallas,ds1340", .data = ds_1340 },
+	{ .compatible = "microchip,mcp7940x", .data = mcp794xx },
 	{ .compatible = "microchip,mcp7941x", .data = mcp794xx },
 	{ .compatible = "st,m41t11", .data = m41t11 },
 	{ }