nvmet: use invalid cmd opcode helper

In the NVMeOF block device backend, file backend, and passthru backend
we reject and report the commands if opcode is not handled.

Use the previously introduced helper in file backend to reduce the
duplicate code and make the error message uniform.
Signed-off-by: NChaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>

drivers/nvme/target/io-cmd-file.c

@@ -400,9 +400,6 @@ u16 nvmet_file_parse_io_cmd(struct nvmet_req *req)
 		req->execute = nvmet_file_execute_write_zeroes;
 		return 0;
 	default:
-		pr_err("unhandled cmd for file ns %d on qid %d\n",
-				cmd->common.opcode, req->sq->qid);
-		req->error_loc = offsetof(struct nvme_common_command, opcode);
-		return NVME_SC_INVALID_OPCODE | NVME_SC_DNR;
+		return nvmet_report_invalid_opcode(req);
 	}
 }