RDMA/bnxt_re: remove unnecessary call to memset

call to memset to assign 0 value immediately after allocating
memory with kzalloc is unnecesaary as kzalloc allocates the memory
filled with 0 value.

Signed-off-by: Himanshu Jha <himanshujha199640@gmail.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>