brcmsmac: rework LED dependencies

This is now the only driver that selects the LEDS_CLASS framework,
which is normally user-selectable. While it doesn't strictly cause
a bug, rework the Kconfig logic to be more consistent with what
other drivers do, and only enable LED support in brcmsmac if the
dependencies are all there, rather than using 'select' to enable
what it needs.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20211204173848.873293-2-arnd@kernel.org