arm64: dts: rockchip: Add leds node to Radxa E20C

arm64: dts: rockchip: Add leds node to Radxa E20C

Radxa E20C has three gpio controlled leds (sys, wan and lan).

Add led nodes and set default trigger to heartbeat for the sys led and
netdev for the lan and wan leds.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Link: https://lore.kernel.org/r/20250304201642.831218-2-jonas@kwiboo.se
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
[ upstream commit: 6a709e003492e9878d5f1357be0b2e1162e1e6a6 ]

(cherry picked from commit a3556ede6b48c7760ac3608ad77601fca26d2ce0)
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>