[MIPS] Fix some system calls with long long arguments

* O32 fadvise64() pass long long arguments by register pairs.  Add
  sys32 version for 64 bit kernel.
* N32 readahead() can pass a long long argument by one register.  No
  need to use sys32_readahead.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --cc arch/mips/kernel/linux32.c
Simple merge

diff --cc arch/mips/kernel/scall64-n32.S
Simple merge

diff --cc arch/mips/kernel/scall64-o32.S
Simple merge