Staging: vme: Enable drivers to handle more than one bridge

At the moment the vme bridge drivers are written in a way that only
allows them to support one bridge at a time. Modify the drivers to
enable more than one bridge to be present per board.

Signed-off-by: Martyn Welch <martyn.welch@ge.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>