libnvdimm: introduce 'flags' attribute for DIMM 'lock' and 'alias' status

Given that we now how have two mechanisms for a DIMM to indicate that it
is locked:

    * NVDIMM_FAMILY_INTEL 'get_config_size' _DSM command

    * ACPI 6.2 Label Storage Read / Write commands

...export the generic libnvdimm DIMM status in a new 'flags' attribute.

This attribute can also reflect the 'alias' state which indicates
whether the nvdimm core is enforcing labels for aliased-region-capacity
that the given dimm is an interleave-set member.
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/dimm_devs.c

@@ -331,6 +331,17 @@ static ssize_t commands_show(struct device *dev,
 }
 static DEVICE_ATTR_RO(commands);
 
+static ssize_t flags_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	struct nvdimm *nvdimm = to_nvdimm(dev);
+
+	return sprintf(buf, "%s%s\n",
+			test_bit(NDD_ALIASING, &nvdimm->flags) ? "alias " : "",
+			test_bit(NDD_LOCKED, &nvdimm->flags) ? "lock " : "");
+}
+static DEVICE_ATTR_RO(flags);
+
 static ssize_t state_show(struct device *dev, struct device_attribute *attr,
 		char *buf)
 {
@@ -372,6 +383,7 @@ static DEVICE_ATTR_RO(available_slots);
 
 static struct attribute *nvdimm_attributes[] = {
 	&dev_attr_state.attr,
+	&dev_attr_flags.attr,
 	&dev_attr_commands.attr,
 	&dev_attr_available_slots.attr,
 	NULL,