power: smb1351: Enable battery-charging by default

Explicitly enable charging via register before configuring
SMB for I2C based charge-enable control. If not done, charging
remains disabled by default.

Change-Id: I02cd3450606b5861ceced3202ca24769e969c8c8
Signed-off-by: Anirudh Ghayal <aghayal@codeaurora.org>