dt-bindings: power: supply: cpcap-battery: update cpcap-battery.yaml reference

Changeset 3c5be045 ("dt-bindings: power: supply: cpcap-battery: Convert to DT schema format")
renamed: Documentation/devicetree/bindings/power/supply/cpcap-battery.txt
to: Documentation/devicetree/bindings/power/supply/cpcap-battery.yaml.

Update its cross-reference accordingly.

Fixes: 3c5be045 ("dt-bindings: power: supply: cpcap-battery: Convert to DT schema format")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/1d0c8d50db22d9e5540a42be874fcd39fb7fc2a7.1622648507.git.mchehab+huawei@kernel.orgSigned-off-by: Rob Herring <robh@kernel.org>

Documentation/devicetree/bindings/mfd/motorola-cpcap.txt

@@ -16,7 +16,7 @@ Optional subnodes:
 The sub-functions of CPCAP get their own node with their own compatible values,
 which are described in the following files:
 
-- Documentation/devicetree/bindings/power/supply/cpcap-battery.txt
+- Documentation/devicetree/bindings/power/supply/cpcap-battery.yaml
 - Documentation/devicetree/bindings/power/supply/cpcap-charger.txt
 - Documentation/devicetree/bindings/regulator/cpcap-regulator.txt
 - Documentation/devicetree/bindings/phy/phy-cpcap-usb.txt