usb: dwc3-msm: Enable wakeup capability irrespective of wakeup_src

Driver currently disables HS and SS PHY async_irqs in host mode
if wakeup sources are not used. This affects wakeup of HUB if it
is selective suspended irrespective of system suspend state.
Also, on system_suspend SS host is anyways stopped and HS PHY works
fine across system suspend. Hence, enable PHYs async_irq in host bus
suspend unconditionally.

Change-Id: Ie814b7454240482c23703a072e8dcaba97fe1e26
Signed-off-by: Manu Gautam <mgautam@codeaurora.org>