net: airoha: Move airoha_qdma pointer in airoha_gdm_dev struct

net: airoha: Move airoha_qdma pointer in airoha_gdm_dev struct

Move airoha_qdma pointer from airoha_gdm_port struct to airoha_gdm_dev
one since the QDMA block used depends on the particular net_device
WAN/LAN configuration and in the current codebase net_device pointer is
associated to airoha_gdm_dev struct.
This is a preliminary patch to support multiple net_devices connected
to the same GDM{3,4} port via an external hw arbiter.

Tested-by: Xuegang Lu <xuegang.lu@airoha.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260527-airoha-eth-multi-serdes-preliminary-v1-2-ec6ed73ef7fc@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>