drm/i915/psr: Split sink status into a separate debugfs node

This allows to read i915_edp_psr_status from tests without triggering
any AUX communication. Take this opportunity to move this under the
eDP-1 connector directory as the status we print is of the sink.

Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Suggested-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180705003121.2478-1-dhinakaran.pandiyan@intel.com