regulator: Add binding for TCS4525

Add a compatible string to support TCS4525/TCS4526 devices,
which are compatible with Fairchild FAN53555 regulators.
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Link: https://lore.kernel.org/r/20210421210338.43819-2-ezequiel@collabora.comSigned-off-by: Mark Brown <broonie@kernel.org>

Documentation/devicetree/bindings/regulator/fan53555.txt

 Binding for Fairchild FAN53555 regulators
 
 Required properties:
-  - compatible: one of "fcs,fan53555", "fcs,fan53526", "silergy,syr827" or
-		"silergy,syr828"
+  - compatible: one of "fcs,fan53555", "fcs,fan53526", "silergy,syr827",
+		"silergy,syr828" or "tcs,tcs4525".
   - reg: I2C address
 
 Optional properties: