net: dsa: b53: Add missing ULL suffix for 64-bit constant

On 32-bit (e.g. with m68k-linux-gnu-gcc-4.1):

    drivers/net/dsa/b53/b53_common.c: In function ‘b53_arl_read’:
    drivers/net/dsa/b53/b53_common.c:1072: warning: integer constant is too large for ‘long’ type

Fixes: 1da6df85 ("net: dsa: b53: Implement ARL add/del/dump operations")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: David S. Miller <davem@davemloft.net>