USB: dwc3: Add support to disable battery charging from USB

Some platforms may not support battery charging from USB port.
Hence, allow users to disable battery charging using DT property.
Also, change name of otg-capability DT property to make it less
verbose.

Change-Id: Ie38f31889f9283d8c682aa7943beb160de05429a
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>