USB: Fix for typo in ohci-ep93xx.c

Attached patch fixes typo in USB driver reported by Chase Douglas on linux-cirrus mailing
list. http://www.freelists.org/archives/linux-cirrus/12-2006/msg00003.html

Signed-off-by: Petr Stetiar <ynezz@true.cz>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>