drm/i915/psr: Modify/Fix Wa_16013835468 and prepare for Wa_14015648006

Wa_16013835468 is a separate from Wa_14015648006 and needs to be
applied for display version 12. Fix this by removing all the
references to Wa_14015648006 and apply Wa_16013835468 according to
Bspec.

Also move workaround into separate function as a preparation for
Wa_14015648006 implementation.

Bspec: 55378

v3:
 - apply for display version 12 only
v2:
 - keep applying the wa in intel_psr_enable_source

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230329150703.432072-3-jouni.hogander@intel.com