usb: wusbcore: preserve endianness of cached descriptors

Do not overwrite the multi-byte fields of usb_wa_descriptor with their
cpu format values after reading the descriptor.  Leave the values as
__le16 and swap on use.  This is more consistent with other uses of USB
descriptors.

Signed-off-by: Thomas Pugliese <thomas.pugliese@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>