drm/i915/display: Allow fastsets when DP_SDP_VSC infoframe do not match with PSR enabled

When PSR is enabled it handles DP_SDP_VSC, changing revision and all
the other fields as necessary.
It can also enabled and disable this SDP as needed without a full
modeset.

So here masking DP_SDP_VSC bit when previous and future state PSR
enabled, it will still be checked when comparing the asked state
to what was programmed to hardware.

Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Radhakrishna Sripada <radhakrishna.sripada@intel.com>
Reported-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Fixes: 78b772e1

 ("drm/i915/display: Fill PSR state during hardware configuration read out")
Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
Reviewed-by: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210514232247.144542-2-jose.souza@intel.com