net/rocker: Cleanup the useless return value check

None of pci_dma_read()'s callers check the return value except
rocker. There is no need to check it because it always return
0. So the check work is useless. Remove it entirely.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Mao Zhongyi <maozy.fnst@cn.fujitsu.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/rocker/rocker.c

@@ -244,11 +244,9 @@ static int tx_consume(Rocker *r, DescInfo *info)
             goto err_no_mem;
         }
 
-        if (pci_dma_read(dev, frag_addr, iov[iovcnt].iov_base,
-                     iov[iovcnt].iov_len)) {
-            err = -ROCKER_ENXIO;
-            goto err_bad_io;
-        }
+        pci_dma_read(dev, frag_addr, iov[iovcnt].iov_base,
+                     iov[iovcnt].iov_len);
+
         iovcnt++;
     }
 
@@ -261,7 +259,6 @@ static int tx_consume(Rocker *r, DescInfo *info)
     err = fp_port_eg(r->fp_port[port], iov, iovcnt);
 
 err_too_many_frags:
-err_bad_io:
 err_no_mem:
 err_bad_attr:
     for (i = 0; i < ROCKER_TX_FRAGS_MAX; i++) {

hw/net/rocker/rocker_desc.c

@@ -69,9 +69,7 @@ char *desc_get_buf(DescInfo *info, bool read_only)
         return NULL;
     }
 
-    if (pci_dma_read(dev, le64_to_cpu(info->desc.buf_addr), info->buf, size)) {
-        return NULL;
-    }
+    pci_dma_read(dev, le64_to_cpu(info->desc.buf_addr), info->buf, size);
 
     return info->buf;
 }