net: Remove unused net-checksum.c file

The common checksum functions were moved to net/checksum.c in commit
7200ac3c but the original net-checksum.c
was never deleted from the source tree.  Remove it now since all users
of the checksum functions link against net/checksum.o and net-checksum.c
is not even compiled anymore.
Signed-off-by: NStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>

net-checksum.c

-/*
- *  IP checksumming functions.
- *  (c) 2008 Gerd Hoffmann <kraxel@redhat.com>
- *
- *  This program is free software; you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation; under version 2 of the License.
- *
- *  This program is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU General Public License for more details.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with this program; if not, see <http://www.gnu.org/licenses/>.
- */
-
-#include "hw/hw.h"
-#include "net.h"
-
-#define PROTO_TCP  6
-#define PROTO_UDP 17
-
-uint32_t net_checksum_add(int len, uint8_t *buf)
-{
-    uint32_t sum = 0;
-    int i;
-
-    for (i = 0; i < len; i++) {
-	if (i & 1)
-	    sum += (uint32_t)buf[i];
-	else
-	    sum += (uint32_t)buf[i] << 8;
-    }
-    return sum;
-}
-
-uint16_t net_checksum_finish(uint32_t sum)
-{
-    while (sum>>16)
-	sum = (sum & 0xFFFF)+(sum >> 16);
-    return ~sum;
-}
-
-uint16_t net_checksum_tcpudp(uint16_t length, uint16_t proto,
-                             uint8_t *addrs, uint8_t *buf)
-{
-    uint32_t sum = 0;
-
-    sum += net_checksum_add(length, buf);         // payload
-    sum += net_checksum_add(8, addrs);            // src + dst address
-    sum += proto + length;                        // protocol & length
-    return net_checksum_finish(sum);
-}
-
-void net_checksum_calculate(uint8_t *data, int length)
-{
-    int hlen, plen, proto, csum_offset;
-    uint16_t csum;
-
-    if ((data[14] & 0xf0) != 0x40)
-	return; /* not IPv4 */
-    hlen  = (data[14] & 0x0f) * 4;
-    plen  = (data[16] << 8 | data[17]) - hlen;
-    proto = data[23];
-
-    switch (proto) {
-    case PROTO_TCP:
-	csum_offset = 16;
-	break;
-    case PROTO_UDP:
-	csum_offset = 6;
-	break;
-    default:
-	return;
-    }
-
-    if (plen < csum_offset+2)
-	return;
-
-    data[14+hlen+csum_offset]   = 0;
-    data[14+hlen+csum_offset+1] = 0;
-    csum = net_checksum_tcpudp(plen, proto, data+14+12, data+14+hlen);
-    data[14+hlen+csum_offset]   = csum >> 8;
-    data[14+hlen+csum_offset+1] = csum & 0xff;
-}