usb: dwc3: msm: Support internal RAM on DBM 1.5

Allow the internal_ram parameter of dbm_ep_config() to be
used to enable the endpoint to access the USB controller's
internal RAM as BAM pipe memory. This is needed for the
QDSS function on MSM8994.

Change-Id: I20046befebced7da9418a34a428f0046c6288c5e
Signed-off-by: Jack Pham <jackp@codeaurora.org>