usb: phy: Add support for PHY based charger detection

The PHY IP supports different circuit blocks like
voltage sources, current sources, comparators and
resistances on the DP/DM lines with the control
by CSR registers.
Add driver support for detecting FLOAT, SDP, CDP
and DCP chargers with the BC1.2 protocol and notifying
the same to the charger driver.
Also, notify the USB connect to the USB driver in case
of SDP and CDP to support enumeration.

Change-Id: I70f0db4f09b09aa24f17485f5ff4debb12384564
Signed-off-by: Sriharsha Allenki <sallenki@codeaurora.org>