linux-yocto/qemuppc: fix console and ethernet

linux-yocto/qemuppc: fix console and ethernet

Two issues are fixed with this commit, the ability to use the keyboard
on a graphical qemu boot and enabling ethernet by default on a 3.0
kernel.

The keyboard is fixed via the same method as the other simulations with
the addition of console=tty on the qemu command line.

Ethernet is fixed by adding a dependency of PCNET32 to the qemuppc
configuration, which allows us to build ethernet directly into the image.

Signed-off-by: Bruce Ashfield <bruce.ashfield@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>