usb: dwc3: msm: allow suspend in host mode

Allow controller enter lpm without power collapse.
Also change the DT flag to 'qcom,ignore-wakeup-src-in-hostmode'.

Change-Id: I49f98ad2c7857c8507fa815c50bdcc13db2cb8b7
Signed-off-by: Linyu Yuan <linyyuan@codeaurora.org>