powerpc/e5500: add networking to defconfig

Even though support for the p5020's on-chip ethernet is not yet upstream,
it is not appropriate to disable all networking support (including
loopback, unix domain sockets, external ethernet devices, etc) in the
defconfig.  The networking settings are taken from mpc85xx_smp_defconfig,
minus the drivers for ethernet devices not found on any current e5500
chip.

The other changes are the result of running "make savedefconfig".

Signed-off-by: Scott Wood <scottwood@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>