USB: OHCI: make ohci-pxa27x a separate driver

Separate the  OHCI pxa27x/pxa3xx host controller driver from
ohci-hcd host code so that it can be built as a separate driver
module. This work is part of enabling multi-platform kernels on
ARM.

Signed-off-by: Manjunath Goudar <manjunath.goudar@linaro.org>
Signed-off-by: Deepak Saxena <dsaxena@linaro.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>