uio: provide vm access to UIO_MEM_PHYS maps

This makes it possible to let gdb access mappings of the process that is
being debugged.

uio_mmap_logical was moved and uio_vm_ops renamed to group related code
and differentiate to new stuff.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>