Prevent multiple lock initialization in e6000sw probe

r319886 ("Add the initial support for the Marvell 88E6141
and 88E6341 switches.") unveiled a problem with possible
multiple lock creation. Move its initialization
to the driver attach and for obtaining the switch ID
create a temprorary one, which is immediately destroyed
after the check.

Submitted by: Zbigniew Bodek <zbb@semihalf.com>

	      Marcin Wojtas <mw@semihalf.com>

Obtained from: Semihalf