drm/i915/dp: Assume panel power is off if runtime suspended

drm/i915/dp: Assume panel power is off if runtime suspended

If the device is runtime suspended the eDP panel power is also off.
Ignore a short HPD on eDP if the device is suspended accordingly,
instead of checking the panel power state via the PPS registers for the
same purpose. The latter involves runtime resuming the device
unnecessarily, in a frequent scenario where the panel generates a
spurious short HPD after disabling the panel power and the device is
runtime suspended.

Reviewed-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241009194358.1321200-2-imre.deak@intel.com