usb: dwc3-msm: Set PROP_BOOST_CURRENT for direct attach devices

If PMIC provides boost power for VBUS in host mode, it may
need to know the amount of current of an attached device
in order to optimize for overall power consumption. We can
pass the bMaxPower obtained from a device's configuration
descriptor when it is attached. This only affects devices
(including hubs) directly attached to the root port, as
any device downstream of a hub will either consume part of
the hub's budget or has external power.

Change-Id: I1ad2cfecb7a2f6bdeaced29a1753cdc1bf3849db
Signed-off-by: Jack Pham <jackp@codeaurora.org>