Fix warnings in arch/arm/cpu/arm920t/s3c24x0/usb_ohci.c

Sorry if this is already fixed somewhere - I could not find it.

This fixes these warnings:

usb_ohci.c: In function 'submit_control_msg':
usb_ohci.c:1081: warning: dereferencing pointer 'data_buf.76' does break strict-aliasing rules
usb_ohci.c:1081: note: initialized from here
usb_ohci.c:1084: warning: dereferencing pointer 'data_buf.76' does break strict-aliasing rules
usb_ohci.c:1084: note: initialized from here
usb_ohci.c:1087: warning: dereferencing pointer 'data_buf.76' does break strict-aliasing rules
usb_ohci.c:1087: note: initialized from here

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Mike Frysinger <vapier@gentoo.org>