[MIPS] open() forces O_LARGEFILE for o32 on 64bit kernels

    
open() always sets the O_LARGEFILE flag for the o32 ABI implementation
of a 64bit kernel. The appended patch fixes it.
    
Signed-off-by: Thiemo Seufer <ths@networkno.de>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>