usb: phy: msm: Add support for secondary PHY control

Allow support to use 2nd HSPHY with USB2 Core.
Some platforms may have configuration to allow USB controller
work with any of the two HSPHYs present. By default driver
configures USB core to use primary HSPHY. Add support to allow
user select 2nd HSPHY using DT parameter.

Signed-off-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Cc: Manu Gautam <mgautam@codeaurora.org>
Signed-off-by: Felipe Balbi <balbi@ti.com>