RDMA/core: Use the DEVICE_ATTR_RO macro

Use the DEVICE_ATTR_RO() helper instead of plain DEVICE_ATTR(), which
makes the code a bit shorter and easier to read.

Link: https://lore.kernel.org/r/20210526132949.20184-1-yuehaibing@huawei.comSigned-off-by: NYueHaibing <yuehaibing@huawei.com>
Signed-off-by: NJason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/core/ucma.c

@@ -1830,13 +1830,12 @@ static struct ib_client rdma_cma_client = {
 };
 MODULE_ALIAS_RDMA_CLIENT("rdma_cm");
 
-static ssize_t show_abi_version(struct device *dev,
-				struct device_attribute *attr,
-				char *buf)
+static ssize_t abi_version_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
 {
 	return sysfs_emit(buf, "%d\n", RDMA_USER_CM_ABI_VERSION);
 }
-static DEVICE_ATTR(abi_version, S_IRUGO, show_abi_version, NULL);
+static DEVICE_ATTR_RO(abi_version);
 
 static int __init ucma_init(void)
 {