extcon: palmas: devicetree: remove non-require property details

Extcon for palma driver does not need vbus supply and hence
removing this from devicetree document/bindings.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Myungjoo Ham <myungjoo.ham@samsung.com>