RDMA/hns: Fix uninitialized variable

A random value will be returned if the condition below is not met, so it
needs to be initialized.

Fixes: 9ea9a53e ("RDMA/hns: Add mapped page count checking for MTR")
Link: https://lore.kernel.org/r/1624011020-16992-3-git-send-email-liweihang@huawei.comSigned-off-by: Yixing Liu <liuyixing1@huawei.com>
Signed-off-by: Weihang Li <liweihang@huawei.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/hns/hns_roce_mr.c

@@ -772,7 +772,7 @@ int hns_roce_mtr_map(struct hns_roce_dev *hr_dev, struct hns_roce_mtr *mtr,
 	struct ib_device *ibdev = &hr_dev->ib_dev;
 	struct hns_roce_buf_region *r;
 	unsigned int i, mapped_cnt;
-	int ret;
+	int ret = 0;
 
 	/*
 	 * Only use the first page address as root ba when hopnum is 0, this