ppc: xilinx-ppc440-generic: Wire LL_TEMAC driver

ppc: xilinx-ppc440-generic: Wire LL_TEMAC driver

If the xparameters file contains a LL_TEMAC definition compile its
driver and the net commands.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.ribalda@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Michal Simek <michal.simek@xilinx.com>