qed: fix the allocation of the chains with an external PBL

Dan reports static checker warning:

"The patch 9b6ee3cf95d3: "qed: sanitize PBL chains allocation" from Jul
23, 2020, leads to the following static checker warning:

drivers/net/ethernet/qlogic/qed/qed_chain.c:299 qed_chain_alloc_pbl()
error: uninitialized symbol 'pbl_virt'.

drivers/net/ethernet/qlogic/qed/qed_chain.c
249 static int qed_chain_alloc_pbl(struct qed_dev *cdev, struct qed_chain *chain)
250 {
251 struct device *dev = &cdev->pdev->dev;
252 struct addr_tbl_entry *addr_tbl;
253 dma_addr_t phys, pbl_phys;
254 __le64 *pbl_virt;
^^^^^^^^^^^^^^^^
[...]
271 if (chain->b_external_pbl)
272 goto alloc_pages;
^^^^^^^^^^^^^^^^ uninitialized
[...]
298 /* Fill the PBL table with the physical address of the page */
299 pbl_virt[i] = cpu_to_le64(phys);
^^^^^^^^^^^
[...]
"

This issue was introduced with commit c3a321b06a80 ("qed: simplify
initialization of the chains with an external PBL"), when
chain->pbl_sp.table_virt initialization was moved up to
qed_chain_init_params().
Fix it by initializing pbl_virt with an already filled chain struct field.

Fixes: c3a321b06a80 ("qed: simplify initialization of the chains with an external PBL")
Reported-by: Dan Carpenter <[e-mail]>
Signed-off-by: Alexander Lobakin <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/qlogic/qed/qed_chain.c

···
 
 	chain->pbl.pp_addr_tbl = addr_tbl;
 
-	if (chain->b_external_pbl)
+	if (chain->b_external_pbl) {
+		pbl_virt = chain->pbl_sp.table_virt;
 		goto alloc_pages;
+	}
 
 	size = array_size(page_cnt, sizeof(*pbl_virt));
 	if (unlikely(size == SIZE_MAX))