dt-bindings: mfd: DA9062/61 MFD binding

Extend existing DA9062 binding information to include the DA9061 PMIC for
MFD core and regulators.

Add a da9062-onkey link to the existing onkey binding file.

Add a da9062-thermal link to the new temperature monitoring binding file.

Delete the da9062-watchdog section and replace it with a link to the new
DA9061/62 binding information file.

Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Steve Twiss <stwiss.opensource@diasemi.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>