USB: OHCI: make ohci-nxp a separate driver

Separate the OHCI NXP 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.

Many place function name and struct name started with usb,
current scenario replaced usb with ohci for proper naming.

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>