uboot-imx

MPC5xxx: fix some compiler warnings in USB code

Fix the following warnings:
- usb.c:xx: warning: function declaration isn't a prototype
- usb_ohci.c:xxx: warning: passing argument 1 of '__fswab32' makes integer
  from pointer wihtout a cast

Signed-off-by: Martin Krause <martin.krase@tqs.de>