board: *_x86: Allow pcie0 to be referenced

Changing pcie0 to pcie0: pcie0 allows it to be referenced as &pcie0. I
am not sure why this is required. Otherwise I get error:

...
parse error: undefined node label 'pcie0'
...

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>