drm/i915/psr: Enable psr2 early transport as possible

Check source and sink support for psr2 early transport and enable
it if not disabled by debug flag.

Bspec: 68934

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Mika Kahola <mika.kahola@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231218175004.52875-7-jouni.hogander@intel.com