This patch changes default implementation of GET_CHIPID from NULL to GENERIC. The purpose of it is to allow sub-sub-drivers to get chip ID.
Reason: There are ethernet switches integrated into MIPS SoC. These switches doesn't provide idents (i.e. has id eq to 0). From device tree perspective they are located under BHND bus > ethernet driver > intermediate bus (SPI or MDIO).
Proposed solution: allow hierarchical call of GET_CHIPID to retrieve SoC ID, so switches can be identified by SoC.