drm/i915/psr: Store pr_dpcd in intel_dp

We need pr_dpcd contents for early transport validity check on eDP Panel
Replay and in debugfs interface to dump out panel early transport
capability. Also remove unnecessarily printing out "Panel replay is not
supported by panel"

v2: commit message modified

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240528114455.175961-2-jouni.hogander@intel.com