Documentation: dt: Intersil isl12057 is not a trivial device

The ISL12057 has a documentation file, remove it from trivial-devices.txt
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

Documentation/devicetree/bindings/i2c/trivial-devices.txt

@@ -50,7 +50,6 @@ fsl,sgtl5000		SGTL5000: Ultra Low-Power Audio Codec
 gmt,g751		G751: Digital Temperature Sensor and Thermal Watchdog with Two-Wire Interface
 infineon,slb9635tt	Infineon SLB9635 (Soft-) I2C TPM (old protocol, max 100khz)
 infineon,slb9645tt	Infineon SLB9645 I2C TPM (new protocol, max 400khz)
-isil,isl12057		Intersil ISL12057 I2C RTC Chip
 isil,isl29028		Intersil ISL29028 Ambient Light and Proximity Sensor
 maxim,ds1050		5 Bit Programmable, Pulse-Width Modulator
 maxim,max1237		Low-Power, 4-/12-Channel, 2-Wire Serial, 12-Bit ADCs