Fix qemu_malloc/qemu_free use in rtl8139.c

rtl8139.c is using malloc()/free() instead of qemu_malloc()/qemu_free().
Fix it.

Signed-off-by: Jean-Christophe DUBOIS <jcd@tribudubois.net>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/hw/rtl8139.c b/hw/rtl8139.c
index c166db0..be47f61 100644
--- a/hw/rtl8139.c
+++ b/hw/rtl8139.c
@@ -1985,7 +1985,7 @@
     if (!s->cplus_txbuffer)
     {
         s->cplus_txbuffer_len = CP_TX_BUFFER_SIZE;
-        s->cplus_txbuffer = malloc(s->cplus_txbuffer_len);
+        s->cplus_txbuffer = qemu_malloc(s->cplus_txbuffer_len);
         s->cplus_txbuffer_offset = 0;
 
         DEBUG_PRINT(("RTL8139: +++ C+ mode transmission buffer allocated space %d\n", s->cplus_txbuffer_len));
@@ -2300,7 +2300,7 @@
         }
         else
         {
-            free(saved_buffer);
+            qemu_free(saved_buffer);
         }
     }
     else