drm/i915/dp_mst: Verify the link status always the same way

drm/i915/dp_mst: Verify the link status always the same way

The MST link status should be always verified from the same DPCD
registers after link training. Atm, both the legacy (0x202 - 0x205) and
the ESI (0x200C - 0x200F) link status registers are used. Use always the
latter ESI version of link status registers.

v2: Propagate error from intel_dp_read_link_status(). (Jani, Luca)

Cc: Jani Nikula <jani.nikula@intel.com>
Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20260225164618.1261368-3-imre.deak@intel.com