drm/vmwgfx: Remove vmw_chipset

vmw_chipset was duplicating pci_id. They are exactly the same
variable just with two different names. Becuase pci_id was
already used to detect the SVGA version, there's no point
in having vmw_chipset and thus we can remove it.

All references to vmw_chipset should use pci_id.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210609172307.131929-9-zackr@vmware.com