linux-user: Fix certain argument alignment cases for Mips64

The function that is changed in this patch is supposed to indicate that
there was certain argument rearrangement related to 64-bit arguments on
32-bit platforms. The background on such rearrangements can be found,
for example, in the man page for syscall(2).

However, for 64-bit Mips architectures there is no such rearrangement,
and this patch reflects it.

Signed-off-by: Aleksandar Rikalo <aleksandar.rikalo@imgtec.com>
Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Leon Alrae <leon.alrae@imgtec.com>
Acked-by: Riku Voipio <riku.voipio@linaro.org>
Signed-off-by: Leon Alrae <leon.alrae@imgtec.com>