rdma/cxgb4: Remove a set-but-not-used variable

This patch avoids that the following warning is reported when building with
W=1:

drivers/infiniband/hw/cxgb4/cm.c:1860:5: warning: variable 'status' set but not used [-Wunused-but-set-variable]
  u8 status;
     ^~~~~~

Fixes: 6a0b6174 ("rdma/cxgb4: Add support for kernel mode SRQ's")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Acked-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>