net: dsa: qca8k: fix LEDS_CLASS dependency

net: dsa: qca8k: fix LEDS_CLASS dependency

With LEDS_CLASS=m, a built-in qca8k driver fails to link:

arm-linux-gnueabi-ld: drivers/net/dsa/qca/qca8k-leds.o: in function `qca8k_setup_led_ctrl':
qca8k-leds.c:(.text+0x1ea): undefined reference to `devm_led_classdev_register_ext'

Change the dependency to avoid the broken configuration.

Fixes: 1e264f9d2918 ("net: dsa: qca8k: add LEDs basic support")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christian Marangi <ansuelsmth@gmail.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://lore.kernel.org/r/20230420213639.2243388-1-arnd@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>