ARM: dts: qcom: Add binding for the qcom coincell charger

This binding is used to configure the driver for the coincell charger
found in Qualcomm PMICs.

Signed-off-by: Tim Bird <tim.bird@sonymobile.com>
Reviewed-by: Andy Gross <agross@codeaurora.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>