drm/i915/pxp/mtl: intel_pxp_init_hw needs runtime-pm inside pm-complete

In the case of failed suspend flow or cases where the kernel does not go
into full suspend but goes from suspend_prepare back to resume_complete,
we get called for a pm_complete but without runtime_pm guaranteed.

Thus, ensure we take the runtime_pm when calling intel_pxp_init_hw
from within intel_pxp_resume_complete.

v2: resume_complete and runtime_resume should abstract a common
    helper with different wakeref requirements. (Daniele)

Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230802190611.1639371-1-alan.previn.teres.alexis@intel.com