drm/i915/psr: Add Early Transport into psr debugfs interface

drm/i915/psr: Add Early Transport into psr debugfs interface

We want to have sink Early Transport capability and usage in our psr
debugfs status interface.

v4: use su_region_et_enabled instead of psr2_su_region_et_valid
v3: remove extra space from "PSR mode:  disabled"
v2: printout "Selective Update enabled (Early Transport)" instead of
    "Selective Update Early Transport enabled"

Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240529093849.1016172-7-jouni.hogander@intel.com