sh/PCI: Use default pcibios_enable_device()

We don't need anything arch-specific in pcibios_enable_device(), so drop
the arch implementation and use the default generic one.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Paul Mundt <lethal@linux-sh.org>
CC: linux-sh@vger.kernel.org