overlays: Fix compatible string for ds1307 RTC

Kernels since 4.19 have required the correct manufacture name in the
compatible string for I2C devices, and unfortunately the one for the
Dallas/Maxim DS1307 should have been "dallas,ds1307" and not
"maxim,ds1307".

See: #3013

Signed-off-by: Phil Elwell <[email protected]>

Author: Phil Elwell

arch/arm/boot/dts/overlays/i2c-rtc-overlay.dts

@@ -30,7 +30,7 @@
 			status = "okay";
 
 			ds1307: ds1307@68 {
-				compatible = "maxim,ds1307";
+				compatible = "dallas,ds1307";
 				reg = <0x68>;
 				status = "okay";
 			};