ARM: kirkwood: Remove unneeded PCIe clock adding

Since the PCIe devices is properly initialized from the DT, the clocks
are now referenced in the device tree nodes, and it's not needed
to have this hack to add them explicitly.

Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Tested-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Tested-by: Arnaud Ebalard <arno@natisbad.org>
Signed-off-by: Jason Cooper <jason@lakedaemon.net>