PCI: kill BKL in /proc/pci

All operations in the pci procfs ioctl functions are
atomic, so no lock is needed here.

Also add a compat_ioctl method, since all the commands
are compatible in 32 bit mode.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: linux-pci@vger.kernel.org
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>