bus: moxtet: remove set but not used variable 'dummy'

Fixes gcc '-Wunused-but-set-variable' warning:

drivers/bus/moxtet.c: In function moxtet_remove:
drivers/bus/moxtet.c:822:6: warning: variable dummy set but not used
[-Wunused-but-set-variable]

Link: https://lore.kernel.org/r/20190822010351.15660-3-marek.behun@nic.cz


Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Marek Behún <marek.behun@nic.cz>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>