platform/x86/dell-wmi-sysman: Make some symbols static

Fix the following sparse warnings:

./passobj-attributes.c:38:23: warning: symbol 'po_is_pass_set' was not declared. Should it be static?
./passobj-attributes.c:70:23: warning: symbol 'po_current_password' was not declared. Should it be static?
./passobj-attributes.c:99:23: warning: symbol 'po_new_password' was not declared. Should it be static?
./passobj-attributes.c:103:23: warning: symbol 'po_min_pass_length' was not declared. Should it be static?
./passobj-attributes.c:107:23: warning: symbol 'po_max_pass_length' was not declared. Should it be static?
./passobj-attributes.c:116:23: warning: symbol 'po_mechanism' was not declared. Should it be static?
./passobj-attributes.c:129:23: warning: symbol 'po_role' was not declared. Should it be static?

Reported-by: Hulk Robot <[e-mail]>
Signed-off-by: Zou Wei <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Hans de Goede <[e-mail]>

drivers/platform/x86/dell-wmi-sysman/passobj-attributes.c

···
 	return ret;
 }
 
-struct kobj_attribute po_is_pass_set =
-		__ATTR_RO(is_enabled);
+static struct kobj_attribute po_is_pass_set = __ATTR_RO(is_enabled);
 
 static ssize_t current_password_store(struct kobject *kobj,
 				      struct kobj_attribute *attr,
···
 	return count;
 }
 
-struct kobj_attribute po_current_password =
-		__ATTR_WO(current_password);
+static struct kobj_attribute po_current_password = __ATTR_WO(current_password);
 
 static ssize_t new_password_store(struct kobject *kobj,
 				  struct kobj_attribute *attr,
···
 	return ret ? ret : count;
 }
 
-struct kobj_attribute po_new_password =
-		__ATTR_WO(new_password);
+static struct kobj_attribute po_new_password = __ATTR_WO(new_password);
 
 attribute_n_property_show(min_password_length, po);
-struct kobj_attribute po_min_pass_length =
-		__ATTR_RO(min_password_length);
+static struct kobj_attribute po_min_pass_length = __ATTR_RO(min_password_length);
 
 attribute_n_property_show(max_password_length, po);
-struct kobj_attribute po_max_pass_length =
-		__ATTR_RO(max_password_length);
+static struct kobj_attribute po_max_pass_length = __ATTR_RO(max_password_length);
 
 static ssize_t mechanism_show(struct kobject *kobj, struct kobj_attribute *attr,
 			 char *buf)
···
 	return sprintf(buf, "password\n");
 }
 
-struct kobj_attribute po_mechanism =
-	__ATTR_RO(mechanism);
+static struct kobj_attribute po_mechanism = __ATTR_RO(mechanism);
 
 static ssize_t role_show(struct kobject *kobj, struct kobj_attribute *attr,
 			 char *buf)
···
 	return -EIO;
 }
 
-struct kobj_attribute po_role =
-	__ATTR_RO(role);
+static struct kobj_attribute po_role = __ATTR_RO(role);
 
 static struct attribute *po_attrs[] = {
 	&po_is_pass_set.attr,