drm/i915/alpm: use variable from intel_crtc_state instead of intel_psr

Currently code is making assumption that PSR is enabled when
intel_alpm_configure is called. This doesn't work if alpm is configured
before PSR is enabled.

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Animesh Manna <animesh.manna@intel.com>
Link: https://lore.kernel.org/r/20250423092334.2294483-2-animesh.manna@intel.com