hw/usb/dev-network.c: Use ldl_le_p() and stl_le_p()

hw/usb/dev-network.c: Use ldl_le_p() and stl_le_p()

Use stl_le_p() and ldl_le_p() to read and write data from
buffers, rather than using pointer casts and cpu_to_le32()
for writes and le32_to_cpup() for reads. This:
 * avoids lots of casts
 * works even if the buffer isn't as aligned as the host would like
 * avoids using the *_to_cpup() functions which we want to get rid of

Note that there may still be some places where a pointer from the
guest is cast to a pointer to a host structure; these would also
have to be changed for the device to work on a host CPU which
enforces alignment restrictions.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-id: 1465573077-29221-1-git-send-email-peter.maydell@linaro.org
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>