powerpc/fsl: Enable CONFIG_E1000E in mpc85xx_smp_defconfig

On the most boards of Freescale platform, they use the PCI-Express
Intel(R) PRO/1000 gigabit ethernet card to work. So enable the
corresponding driver for it.

Signed-off-by: Chunhe Lan <Chunhe.Lan@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>