qcacmn: Allocate IPA TX skb buffers with srng unlocked

On low memory system, skb allocation failures are observed in
dp_tx_ipa_uc_attach during driver loading phase. Per kernel
memory team analysis, failures are caused by large amount of
atomic allocations. Currently when allocating IPA TX skbs,
srng spinlock is first grabbed and then skb buffers are being
requested, which makes skb allocation happen in atomic context.

Fix is to make skb allocations with srng unlocked since it is
safe for race conditions during driver loading time. This ensures
skb allocations in process context.

Change-Id: I1624276c087c8247d672fb7cea5daded07ab93a3
CRs-Fixed: 2426489

dp/wifi3.0/dp_ipa.c

@@ -234,7 +234,7 @@ static int dp_tx_ipa_uc_attach(struct dp_soc *soc, struct dp_pdev *pdev)
 		return -ENOMEM;
 	}
 
-	hal_srng_access_start(soc->hal_soc, (void *)wbm_srng);
+	hal_srng_access_start_unlocked(soc->hal_soc, (void *)wbm_srng);
 
 	/*
 	 * Allocate Tx buffers as many as possible
@@ -276,7 +276,7 @@ static int dp_tx_ipa_uc_attach(struct dp_soc *soc, struct dp_pdev *pdev)
 			__dp_ipa_handle_buf_smmu_mapping(soc, nbuf, true);
 	}
 
-	hal_srng_access_end(soc->hal_soc, wbm_srng);
+	hal_srng_access_end_unlocked(soc->hal_soc, wbm_srng);
 
 	soc->ipa_uc_tx_rsc.alloc_tx_buf_cnt = tx_buffer_count;