drm/i915/psr: Take into account SU SDP scanline indication in vblank check

drm/i915/psr: Take into account SU SDP scanline indication in vblank check

SU SDP scanline indication should be taken into account when checking
vblank length. In Bspec we have:

PSR2_CTL[ SU SDP scanline indication ] = 0: (TRANS_VBLANK Vertical Blank
End- TRANS_VBLANK Vertical Blank Start) > PSR2_CTL Block Count Number value
in lines

PSR2_CTL[ SU SDP scanline indication ] = 1: (TRANS_VBLANK Vertical Blank
End- TRANS_VBLANK Vertical Blank Start- 1) > PSR2_CTL Block Count Number
value in lines

Bspec: 49274

Signed-off-by: Jouni Högander <jouni.hogander@intel.com>
Reviewed-by: Animesh Manna <animesh.manna@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240607134917.1327574-12-jouni.hogander@intel.com