Replace mac[5] += offset with a proper 48-bit MAC address add to avoid
overflow issues when mac[5] was close to 255.
Example:
i.MX95 MAC2: 00:11:22:33:44:FE + 6
Old: 00:11:22:33:44:04 (overflow, wraps to 0)
New: 00:11:22:33:45:04 (correct carry from mac[5] to mac[4])
Signed-off-by: Alice Guo <alice.guo@nxp.com>
Signed-off-by: Ye Li <ye.li@nxp.com>
Reviewed-by: Peng Fan <peng.fan@nxp.com>