drm/i915/dp: Fix readback for target_rr in Adaptive Sync SDP

Correct the bit-shift logic to properly readback the 10 bit target_rr from
DB3 and DB4.

v2: Align the style with readback for vtotal. (Ville)

Fixes: 12ea892 ("drm/i915/dp: Add Read/Write support for Adaptive Sync SDP")
Cc: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
Cc: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patch.msgid.link/20260511123218.1589830-2-ankit.k.nautiyal@intel.com
(cherry picked from commit f7abc4a)
Signed-off-by: Tvrtko Ursulin <tursulin@ursulin.net>

Author: aknautiyal

drivers/gpu/drm/i915/display/intel_dp.c

@@ -5303,7 +5303,7 @@ int intel_dp_as_sdp_unpack(struct drm_dp_as_sdp *as_sdp,
 	as_sdp->length = sdp->sdp_header.HB3 & DP_ADAPTIVE_SYNC_SDP_LENGTH;
 	as_sdp->mode = sdp->db[0] & DP_ADAPTIVE_SYNC_SDP_OPERATION_MODE;
 	as_sdp->vtotal = (sdp->db[2] << 8) | sdp->db[1];
-	as_sdp->target_rr = (u64)sdp->db[3] | ((u64)sdp->db[4] & 0x3);
+	as_sdp->target_rr = ((sdp->db[4] & 0x3) << 8) | sdp->db[3];
 	as_sdp->target_rr_divider = sdp->db[4] & 0x20 ? true : false;
 
 	return 0;