MIPS: Fix gigaton of warning building with microMIPS.

With binutils 2.24 the attempt to switch with microMIPS mode to MIPS III
mode through .set mips3 results in *lots* of warnings like

{standard input}: Assembler messages:
{standard input}:397: Warning: the 64-bit MIPS architecture does not support the `smartmips' extension

during a kernel build.  Fixed by using .set arch=r4000 instead.

This breaks support for building the kernel with binutils 2.13 which
was supported for 32 bit kernels only anyway and 2.14 which was a bad
vintage for MIPS anyway.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

diff --cc arch/mips/alchemy/common/sleeper.S
Simple merge

diff --cc arch/mips/include/asm/asm.h
Simple merge

diff --cc arch/mips/include/asm/atomic.h
Simple merge

diff --cc arch/mips/include/asm/bitops.h
Simple merge

diff --cc arch/mips/include/asm/cmpxchg.h
Simple merge

diff --cc arch/mips/include/asm/futex.h
Simple merge

diff --cc arch/mips/include/asm/io.h
Simple merge

diff --cc arch/mips/include/asm/local.h
Simple merge

diff --cc arch/mips/include/asm/mach-pmcs-msp71xx/msp_regops.h
Simple merge

diff --cc arch/mips/include/asm/r4kcache.h
Simple merge

diff --cc arch/mips/include/asm/stackframe.h
Simple merge

diff --cc arch/mips/kernel/bmips_vec.S
Simple merge

diff --cc arch/mips/kernel/genex.S
Simple merge

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

diff --cc arch/mips/kernel/r4k_fpu.S
Simple merge

diff --cc arch/mips/kernel/r4k_switch.S
Simple merge

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

diff --cc arch/mips/pmcs-msp71xx/msp_setup.c
Simple merge