smb-lib: add support of DP/DM pulsing for fix 5V, 9V and 12V

This change will enable userspace to control adapter's output
voltage. Userspace can force adapter's output voltage to
5V/9V/12V.

Change-Id: I4a60a681c136df6864294dbd19849503a2be2e7b
Signed-off-by: Umang Agrawal <uagrawal@codeaurora.org>