rtl8187se: Use a dir under /proc/net/r8180/

Create a dir under /proc/net/r8180/ named for the device and create that
device's files under there.  This means that there won't be a problem for
multiple devices in the system (if such is possible) and it means we don't
need to save the 'device directory' PDE any more as we can just do a proc
subtree removal.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
cc: Maxim Mikityanskiy <maxtram95@gmail.com>
cc: YAMANE Toshiaki <yamanetoshi@gmail.com>
cc: linux-wireless@vger.kernel.org
cc: devel@driverdev.osuosl.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>