gpio: rockchip: Use gpio alias id as gpio bank id

The U-Boot driver try to base the gpio bank id on the gpio-ranges prop
and fall back to base the bank id on the node name. However, the linux
driver try to base the bank id on the gpio alias id and fall back on
node order.

This can cause issues when SoC DT is synced from linux and gpioX@ nodes
has been renamed to gpio@ and gpio-ranges or a SoC specific alias has
not been assigned.

Try to use the gpio alias id as first fallback when a gpio-ranges prop
is missing to ease sync of updated SoC DT. Keep the current fallback on
node name as a third fallback to not affect any existing unsynced DT.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Quentin Schulz <quentin.schulz@theobroma-systems.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>