USB: fix mos7840 problem with minor numbers

commit 37768adf9a1d49aeac0db1ba3dc28b3274b7b789 upstream

This patch fixes a problem with any mos7840 device where the use of the
field "minor" before it is initialised results in all the devices being
overlaid in memory (minor = 0 for all instances)

Contributed by: Phillip Branch

Backported to .27 by Christoph Biedl <linux-kernel.bfrz@manchmal.in-ulm.de>

Signed-off-by: Tony Cook <tony-cook@bigpond.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>