usb: pd: fix compilation errors

Fix compilation errors introduced during the snapshot from
msm-4.14 and subsequent cherry-picks.

 - Add missing linux/usb/usbpd.h header
 - Upstream moved extcon definitions to <linux/extcon-provider.h>
 - Fix missing space after '=' in Makefile, otherwise 'pd'
   subdirectory fails to be included
 - Fix a few places where break/return were incorrectly used
 - MSG_BATTERY_STATUS is not an extended message so handling
   should have been done in handle_data_snk_ready()

Change-Id: I248b17a8479572b53b2a792877460d6474bca113
Signed-off-by: Jack Pham <jackp@codeaurora.org>