hw/net: pcnet: Remove the logic of padding short frames in the receiv…

…e path

Now that we have implemented unified short frames padding in the
QEMU networking codes, remove the same logic in the NIC codes.

Signed-off-by: Bin Meng <bmeng@tinylab.org>
Signed-off-by: Jason Wang <jasowang@redhat.com>

hw/net/pcnet.c

@@ -987,7 +987,6 @@ ssize_t pcnet_receive(NetClientState *nc, const uint8_t *buf, size_t size_)
 {
     PCNetState *s = qemu_get_nic_opaque(nc);
     int is_padr = 0, is_bcast = 0, is_ladr = 0;
-    uint8_t buf1[60];
     int remaining;
     int crc_err = 0;
     size_t size = size_;
@@ -1000,14 +999,6 @@ ssize_t pcnet_receive(NetClientState *nc, const uint8_t *buf, size_t size_)
     printf("pcnet_receive size=%zu\n", size);
 #endif
 
-    /* if too small buffer, then expand it */
-    if (size < MIN_BUF_SIZE) {
-        memcpy(buf1, buf, size);
-        memset(buf1 + size, 0, MIN_BUF_SIZE - size);
-        buf = buf1;
-        size = MIN_BUF_SIZE;
-    }
-
     if (CSR_PROM(s)
         || (is_padr=padr_match(s, buf, size))
         || (is_bcast=padr_bcast(s, buf, size))