sh: pci: Use a generic raw spinlock for PCI config access locking.

This copies the pci_config_lock idea from x86 over, allowing us to kill
off a couple of existing private locks. At the same time, these need to
be converted to raw spinlocks for -rt kernels, so we make that change at
the same time. This should make it easier for future parts to get the
locking right instead of inevitable ending up with lock type mismatches.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>