wireless: carl9170: fix LEDS build errors & warnings

kernel test robot reports over 200 build errors and warnings
that are due to this Kconfig problem when CARL9170=m,
MAC80211=y, and LEDS_CLASS=m.

WARNING: unmet direct dependencies detected for MAC80211_LEDS
  Depends on [n]: NET [=y] && WIRELESS [=y] && MAC80211 [=y] && (LEDS_CLASS [=m]=y || LEDS_CLASS [=m]=MAC80211 [=y])
  Selected by [m]:
  - CARL9170_LEDS [=y] && NETDEVICES [=y] && WLAN [=y] && WLAN_VENDOR_ATH [=y] && CARL9170 [=m]

CARL9170_LEDS selects MAC80211_LEDS even though its kconfig
dependencies are not met. This happens because 'select' does not follow
any Kconfig dependency chains.

Fix this by making CARL9170_LEDS depend on MAC80211_LEDS, where
the latter supplies any needed dependencies on LEDS_CLASS.

Fixes: 1d7e1e6b ("carl9170: Makefile, Kconfig files and MAINTAINERS")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: kernel test robot <lkp@intel.com>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: Christian Lamparter <chunkeey@googlemail.com>
Cc: linux-wireless@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>
Suggested-by: Christian Lamparter <chunkeey@googlemail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Christian Lamparter <chunkeey@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20210530031134.23274-1-rdunlap@infradead.org