powerpc/82xx/km: add testpin detection for mgcoge3ne

On mgcoge3ne we also want to start the test application if the testpin
is asserted. But we don't have a full POST test support yet. So simply
add a function to read the testpin value.

Signed-off-by: Holger Brunck <holger.brunck@keymile.com>
Signed-off-by: Valentin Longchamp <valentin.longchamp@keymile.com>
3 files changed