iwlwifi: pcie: avoid potential PNVM leaks

If we erroneously try to set the PNVM data again after it has
already been set, we could leak the old DMA memory. Avoid that
and warn, we shouldn't be doing this.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Fixes: 69725928 ("iwlwifi: read and parse PNVM file")
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/iwlwifi.20210115130252.929c2d680429.I086b9490e6c005f3bcaa881b617e9f61908160f3@changeid

drivers/net/wireless/intel/iwlwifi/pcie/ctxt-info-gen3.c

@@ -294,6 +294,9 @@ int iwl_trans_pcie_ctx_info_gen3_set_pnvm(struct iwl_trans *trans,
 		return ret;
 	}
 
+	if (WARN_ON(prph_sc_ctrl->pnvm_cfg.pnvm_size))
+		return -EBUSY;
+
 	prph_sc_ctrl->pnvm_cfg.pnvm_base_addr =
 		cpu_to_le64(trans_pcie->pnvm_dram.physical);
 	prph_sc_ctrl->pnvm_cfg.pnvm_size =