fix(sm8250): drop duplicate cpu7_opp21 label on Xiaoxin Pad Pro overclock OPP

Patch 0020 adds an overclock OPP at 3.1872 GHz to &cpu7_opp_table but
labels it 'cpu7_opp21', which already names opp-3091200000 in upstream
sm8250.dtsi. dtc rejects the resulting tree with:

  ERROR (duplicate_label): /opp-table-cpu7/opp-3187200000:
  Duplicate label 'cpu7_opp21' on /opp-table-cpu7/opp-3187200000
                            and /opp-table-cpu7/opp-3091200000

This breaks `make dtbs` for the entire sm8250 family - any board build
in that family (e.g. dg-svr-865-tiny) fails even though it does not use
the Lenovo DTB itself.

The label is never referenced, so drop it. Applied to both the 6.18 and
6.19 archive patches.

Author: igorpecovnik

patch/kernel/archive/sm8250-6.18/0020-arm64-dts-qcom-add-device-tree-for-Xiaoxin-Pad-Pro-1.patch

@@ -57,7 +57,7 @@ index 000000000000..86a4885d1b57
 +/delete-node/ &cdsp_secure_heap;
 +
 +&cpu7_opp_table {
-+	cpu7_opp21: opp-3187200000 {
++	opp-3187200000 {
 +		opp-hz = /bits/ 64 <3187200000>;
 +		opp-peak-kBps = <8368000 51609600>;
 +	};

patch/kernel/archive/sm8250-6.19/0020-arm64-dts-qcom-add-device-tree-for-Xiaoxin-Pad-Pro-1.patch

@@ -57,7 +57,7 @@ index 000000000000..86a4885d1b57
 +/delete-node/ &cdsp_secure_heap;
 +
 +&cpu7_opp_table {
-+	cpu7_opp21: opp-3187200000 {
++	opp-3187200000 {
 +		opp-hz = /bits/ 64 <3187200000>;
 +		opp-peak-kBps = <8368000 51609600>;
 +	};