rockchip: don't disable timer LED trigger

The timer LED trigger is enabled in all targets (except for lantiq
xway-legacy). It's necessary for the OpenWrt preinit LED pattern to
work.

Signed-off-by: David Bauer <[email protected]>

target/linux/rockchip/armv8/config-5.4

@@ -229,7 +229,6 @@ CONFIG_LEDS_SYSCON=y
 CONFIG_LEDS_TRIGGER_CPU=y
 CONFIG_LEDS_TRIGGER_HEARTBEAT=y
 CONFIG_LEDS_TRIGGER_PANIC=y
-# CONFIG_LEDS_TRIGGER_TIMER is not set
 CONFIG_LEGACY_PTYS=y
 CONFIG_LEGACY_PTY_COUNT=16
 CONFIG_LIBCRC32C=y