phy: msm: qusb: Add support for USB HS AC/DC coupling

Add support for USB HS AC/DC coupling feature in QUSB PHY driver.
Specifically, parse the register, bitmask and the value which
specify the value to be written to the register to control the
DP/DM signal flow mux (cap/non-cap).

Change-Id: Ib9a7730eccb60e7c36424f841924d7e54cd56a0b
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>