gpio: Raise exception on GPIO lookup failure

This allows dbus calls to gpioInit to fail instead of only returning a
default value. This behavior allows the C-side GPIO lookup to error out
as expected.

Signed-off-by: Xo Wang <xow@google.com>
Change-Id: I13ad20de5d209716f26e46c12ca6941eb3dd5997
1 file changed