usb: dwc3-msm: Allow PM suspend in host mode irrespective of runtimePM

DWC3 driver uses wakeup_source and allows pm_suspend only after
entering low power mode as part of runtime suspend. This prevents
PM suspend in host mode if connected device and its driver doesn't
support runtime or selective suspend.
Add support in driver where user can specify using dtsi attribute
to not use wakeup source in host mode. It will allow system to enter
deep sleep or pm_suspend irrespective of runtime PM state of XHCI.
Also, super-speed PHY cannot be suspended in SS mode bus-suspend.
Allowing PM suspend without SS PHY wouldn't give much power
savings as XO and VMIN can't happen. For this reason force host
mode disconnect if SS host mode so that SS PHY can be suspended.
On high level below are the changes in default behavior:
 -Do not use wakeup_source for DWC3 when operating in host mode.
 -For HS host mode, devices will suspend upon PM suspend and resumed
  after PM resume in case not runtime suspended already.
 -For SS host mode stop host before PM suspend start host on PM resume.

CRs-fixed: 2009301
Change-Id: I3749b96296cfc86428bdd4da4ce9c70fb4e4b98c
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>