net: rnpgbe: Add register_netdev

net: rnpgbe: Add register_netdev

Complete the network device (netdev) registration flow for Mucse Gbe
Ethernet chips, including:
1. Hardware state initialization:
   - Send powerup notification to firmware (via echo_fw_status)
   - Sync with firmware
   - Reset hardware
2. MAC address handling:
   - Retrieve permanent MAC from firmware (via mucse_mbx_get_macaddr)
   - Fallback to random valid MAC (eth_random_addr) if not valid mac
     from Fw

Signed-off-by: Dong Yibo <dong100@mucse.com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/20251101013849.120565-6-dong100@mucse.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>