usb: dwc3-msm: Prevent switch to peripheral for host-mode only core

Currently certain platforms have cores which are only host-mode
compatible. Prevent switch to peripharal mode for such cores so
as to prevent unanticipated core behavior and crashes.

Change-Id: I163e878bfe7428ed339409adb8a491a6673ca055
Signed-off-by: Harsh Agarwal <harshq@codeaurora.org>