atl1c: refine mac address related code

On some platform with EEPROM/OTP existing, the BIOS could overwrite
a new MAC address for the NIC. so, the permanent mac address should
be from BIOS. the address is restored when driver removing.
Voltage raising isn't applicable for l1d.
Replace swab32 with htonl for big/little endian platform.
related Registers are refined as well.

Signed-off-by: xiong <xiong@qca.qualcomm.com>
Tested-by: Liu David <dwliu@qca.qualcomm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>