PCI: Remove pci_mmap_page_range() wrapper

The ARCH_GENERIC_PCI_MMAP_RESOURCE symbol came up in a recent discussion,
and I noticed that this was left behind by an unfinished cleanup from 2017.

The only architecture that still relies on providing its own
pci_mmap_page_range() helper instead of using the generic
pci_mmap_resource_range() is sparc. Presumably the reasons for this have
not changed, but at least this can be simplified by converting sparc to use
the same interface as the others.

The only difference between the two is the device-specific offset that gets
added to or subtracted from vma->vm_pgoff.

Change the only caller of pci_mmap_page_range() in common code to subtract
this offset and call the modern interface, while adding it back in the
sparc implementation to preserve the existing behavior.

This removes the complexities of the dual interfaces from the common code,
and keeps it all specific to the sparc architecture code. According to
David Miller, the sparc code lets user space poke into the VGA I/O port
registers by mmapping the I/O space of the parent bridge device, which is
something that the generic pci_mmap_resource_range() code apparently does
not.

Link: https://lore.kernel.org/lkml/1519887203.622.3.camel@infradead.org/t/
Link: https://lore.kernel.org/lkml/20220714214657.2402250-3-shorne@gmail.com/
Link: https://lore.kernel.org/r/20220715153617.3393420-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Stafford Horne <shorne@gmail.com>

Documentation: better locations for sysfs-pci, sysfs-tagging

sysfs-pci and sysfs-tagging were mis-filed: their locations within
Documentation/ implied that they were related to file systems. Actually,
each topic is about a very specific *use* of sysfs, and sysfs *happens*
to be a (virtual) filesystem, so this is not really the right place.

It's jarring to be reading about filesystems in general and then come
across these specific details about PCI, and tagging...and then back to
general filesystems again.

Move sysfs-pci to PCI, and move sysfs-tagging to networking. (Thanks to
Jonathan Corbet for coming up with the final locations.)

Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Link: https://lore.kernel.org/r/20201009070128.118639-1-jhubbard@nvidia.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>