This patch abstracts out a AMD chipset type which includes southbridge
generation and its revision. When os excutes usb_amd_find_chipset_info
routine to initialize AMD chipset type, driver will know which kind of
chipset is used.

This update has below benifits:
- Driver is able to confirm which southbridge generations and their
  revision are used, with chipset detection once.
- To describe chipset generations with enumeration types brings better
  readability.
- It's flexible to filter AMD platforms to implement new quirks in future.
Signed-off-by: Huang Rui <ray.huang@amd.com>
Cc: Andiry Xu <andiry.xu@gmail.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>