ARM: dts: msm: add charger device for PM855B

Specify the configuration for charger device that is present on
PM855B, which will be used for SDM855 platforms.

Also add VBUS and VCONN regulator configurations in the SDM855
PMIC overlay so that they can be included in SDM855 platforms.

Change-Id: I365d770bc868d375d3dc66d5978c8777151da780
Signed-off-by: Harry Yang <harryy@codeaurora.org>