xhci: split into multiple files

Moved structs and defines to hcd-xhci.h.
Move nec controller variant to hcd-xhci-nec.c.
No functional changes.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Message-id: 20170517103313.8459-1-kraxel@redhat.com
4 files changed