ehci-platform: add pre_setup() method to platform data

Sometimes there is a need  to initialize some non-standard registers mapped to
the EHCI region before accessing the standard EHCI registers.  Add pre_setup()
method with 'struct usb_hcd *' parameter to be called just before ehci_setup()
to the 'ehci-platform'  driver's platform data for this purpose...

While at it, add the missing incomplete declaration of 'struct platform_device'
to <linux/usb/ehci_pdriver.h>...

The patch has been tested on the Marzen and BOCK-W boards.

Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Acked-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>