batman-adv: Disable CONFIG_BATMAN_ADV_SYSFS by default

The sysfs support in batman-adv is deprecated since a while and will be
removed completely next year.

All tools which were known to the batman-adv development team are
supporting the batman-adv netlink interface since a while. Thus
disabling CONFIG_BATMAN_ADV_SYSFS by default should not cause problems on
most systems. It is still possible to enable it in case it is still
required in a specific setup.

Signed-off-by: Sven Eckelmann <[e-mail]>
Signed-off-by: Simon Wunderlich <[e-mail]>

net/batman-adv/Kconfig

···
 config BATMAN_ADV_SYSFS
 	bool "batman-adv sysfs entries"
 	depends on BATMAN_ADV
-	default y
 	help
 	  Say Y here if you want to enable batman-adv device configuration and
 	  status interface through sysfs attributes. It is replaced by the