RDMA/erdma: Using the key in FMR WR instead of MR structure

RDMA driver should get the MR key from FMR WR, not the MR structure passed
in.

Fixes: 1550557 ("RDMA/erdma: Add verbs implementation")
Link: https://lore.kernel.org/r/20220810014320.88026-2-chengyou@linux.alibaba.com
Signed-off-by: Cheng Xu <chengyou@linux.alibaba.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>

Author: hz-cheng

drivers/infiniband/hw/erdma/erdma_qp.c

@@ -407,7 +407,7 @@ static int erdma_push_one_sqe(struct erdma_qp *qp, u16 *pi,
 			     to_erdma_access_flags(reg_wr(send_wr)->access);
 		regmr_sge->addr = cpu_to_le64(mr->ibmr.iova);
 		regmr_sge->length = cpu_to_le32(mr->ibmr.length);
-		regmr_sge->stag = cpu_to_le32(mr->ibmr.lkey);
+		regmr_sge->stag = cpu_to_le32(reg_wr(send_wr)->key);
 		attrs = FIELD_PREP(ERDMA_SQE_MR_MODE_MASK, 0) |
 			FIELD_PREP(ERDMA_SQE_MR_ACCESS_MASK, mr->access) |
 			FIELD_PREP(ERDMA_SQE_MR_MTT_CNT_MASK,