misc: genwqe: fix compile warnings

misc: genwqe: fix compile warnings

Using the following command will get compile warnings:
make W=1 drivers/misc/genwqe/card_ddcb.o ARCH=x86_64

drivers/misc/genwqe/card_ddcb.c: In function setup_ddcb_queue:
drivers/misc/genwqe/card_ddcb.c:1024:6: warning: variable rc set but not
used [-Wunused-but-set-variable]
drivers/misc/genwqe/card_ddcb.c: In function genwqe_card_thread:
drivers/misc/genwqe/card_ddcb.c:1190:23: warning: variable rc set but
not used [-Wunused-but-set-variable]

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Hongbo Yao <yaohongbo@huawei.com>
Link: https://lore.kernel.org/r/20191205111655.170382-1-yaohongbo@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>