sysfs: Introduce DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE()

One of the first users of DEFINE_SYSFS_GROUP_VISIBLE() did this:

	static umode_t dp0_attr_visible(struct kobject *kobj,
					struct attribute *attr,
					int n)
	{
		struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj));

		if (slave->prop.dp0_prop)
			return attr->mode;
		return 0;
	}

	static bool dp0_group_visible(struct kobject *kobj)
	{
		struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj));

		if (slave->prop.dp0_prop)
			return true;
		return false;
	}
	DEFINE_SYSFS_GROUP_VISIBLE(dp0);

...i.e. the _group_visible() helper is identical to the _attr_visible()
helper. Use the "simple" helper to reduce that to:

	static bool dp0_group_visible(struct kobject *kobj)
	{
		struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj));

		if (slave->prop.dp0_prop)
			return true;
		return false;
	}
	DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(dp0);

Remove the need to specify per attribute visibility if the goal is to
hide the entire group.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/170863446625.1479840.10593839479268727913.stgit@dwillia2-xfh.jf.intel.com


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>