Here the local hexbuf is a duplicate of global const char hex_asc from
lib/hexdump.c, except the hex letters' cases:
	const char hexbuf[] = "
0123456789ABCDEF";
	const char hex_asc[] = "
0123456789abcdef";
and here to print HW addresses, the hex cases are not significant.
Thanks to Harvey Harrison to introduce the hex_asc_hi/hex_asc_lo helpers.
Signed-off-by: Denis Cheng <crquan@gmail.com>
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
                                   struct neighbour *n)
 {
        char hbuffer[HBUFFERLEN];
-       const char hexbuf[] = "0123456789ABCDEF";
        int k, j;
        char tbuf[16];
        struct net_device *dev = n->dev;
        else {
 #endif
        for (k = 0, j = 0; k < HBUFFERLEN - 3 && j < dev->addr_len; j++) {
-               hbuffer[k++] = hexbuf[(n->ha[j] >> 4) & 15];
-               hbuffer[k++] = hexbuf[n->ha[j] & 15];
+               hbuffer[k++] = hex_asc_hi(n->ha[j]);
+               hbuffer[k++] = hex_asc_lo(n->ha[j]);
                hbuffer[k++] = ':';
        }
        hbuffer[--k] = 0;