ethoc: fix library build errors

ethoc indirectly uses crc32_le() and bitrev32(), so select
those library functions to be built.

drivers/built-in.o: In function `ethoc_set_multicast_list':
ethoc.c:(.text+0x6226f): undefined reference to `crc32_le'
ethoc.c:(.text+0x62276): undefined reference to `bitrev32'

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>