RDMA/bnxt_re: Remove unneeded variable

Fix the following coccicheck review:
./drivers/infiniband/hw/bnxt_re/main.c: 896: 5-7: Unneeded variable

Remove unneeded variable used to store return value.

Link: https://lore.kernel.org/r/20211109113227.132596-1-deng.changcheng@zte.com.cn
Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Changcheng Deng <deng.changcheng@zte.com.cn>
Reviewed-by: Devesh Sharma <devesh.s.sharma@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>