[RTL] Mask MLDSA private key writes when KV data is present (#237)

* masks writes to MLDSA private key in API access when mlkem msg data from the keyvault is present
mlkem msg data is stored in part of the SK memory and could potentially be overwritten partially using the MLDSA private key

* MICROSOFT AUTOMATED PIPELINE: Stamp 'user/dev/michnorris/kv_bugfix' with updated timestamp and hash after successful run

Author: Nitsirks

.github/workflow_metadata/pr_hash

@@ -1 +1 @@
-9f509918a32aef8928aa0d046adc9000cc660627986d7977e6e72b0fe2ca57f852d96f6a980044075796b22e1fb3a665
+36b15d8b679cff273caa9ec38db99ae9a9b4476879d48f69c81747f082a0a9c800b1def2764c7e220458ae4792d7231e

.github/workflow_metadata/pr_timestamp

@@ -1 +1 @@
-1762818050
+1762905412

src/abr_top/rtl/abr_ctrl.sv

@@ -913,7 +913,7 @@ always_comb kv_mlkem_msg_write_data = '0;
   always_comb api_sk_raddr = abr_reg_hwif_out.MLDSA_PRIVKEY_OUT.addr[12:2];
 
   always_comb api_sk_reg_wr_dec = abr_reg_hwif_out.MLDSA_PRIVKEY_IN.req & api_sk_waddr inside {[0:31]};
-  always_comb api_keymem_wr_dec = abr_reg_hwif_out.MLDSA_PRIVKEY_IN.req & api_sk_waddr inside {[31:PRIVKEY_NUM_DWORDS-1]};
+  always_comb api_keymem_wr_dec = abr_reg_hwif_out.MLDSA_PRIVKEY_IN.req & api_sk_waddr inside {[31:PRIVKEY_NUM_DWORDS-1]} & ~kv_mlkem_msg_data_present;
 
   always_comb api_sk_reg_rd_dec = abr_reg_hwif_out.MLDSA_PRIVKEY_OUT.req & api_sk_raddr inside {[0:31]};
   always_comb api_keymem_rd_dec = abr_reg_hwif_out.MLDSA_PRIVKEY_OUT.req & api_sk_raddr inside {[32:PRIVKEY_NUM_DWORDS-1]};