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 --git a/arch/mips/include/asm/futex.h b/arch/mips/include/asm/futex.h
index 1fe2cd6..194cda0 100644
--- a/arch/mips/include/asm/futex.h
+++ b/arch/mips/include/asm/futex.h
@@ -23,11 +23,11 @@
 		__asm__ __volatile__(					\
 		"	.set	push				\n"	\
 		"	.set	noat				\n"	\
-		"	.set	mips3				\n"	\
+		"	.set	arch=r4000			\n"	\
 		"1:	ll	%1, %4	# __futex_atomic_op	\n"	\
 		"	.set	mips0				\n"	\
 		"	" insn	"				\n"	\
-		"	.set	mips3				\n"	\
+		"	.set	arch=r4000			\n"	\
 		"2:	sc	$1, %2				\n"	\
 		"	beqzl	$1, 1b				\n"	\
 		__WEAK_LLSC_MB						\
@@ -49,11 +49,11 @@
 		__asm__ __volatile__(					\
 		"	.set	push				\n"	\
 		"	.set	noat				\n"	\
-		"	.set	mips3				\n"	\
+		"	.set	arch=r4000			\n"	\
 		"1:	"user_ll("%1", "%4")" # __futex_atomic_op\n"	\
 		"	.set	mips0				\n"	\
 		"	" insn	"				\n"	\
-		"	.set	mips3				\n"	\
+		"	.set	arch=r4000			\n"	\
 		"2:	"user_sc("$1", "%2")"			\n"	\
 		"	beqz	$1, 1b				\n"	\
 		__WEAK_LLSC_MB						\
@@ -147,12 +147,12 @@
 		"# futex_atomic_cmpxchg_inatomic			\n"
 		"	.set	push					\n"
 		"	.set	noat					\n"
-		"	.set	mips3					\n"
+		"	.set	arch=r4000				\n"
 		"1:	ll	%1, %3					\n"
 		"	bne	%1, %z4, 3f				\n"
 		"	.set	mips0					\n"
 		"	move	$1, %z5					\n"
-		"	.set	mips3					\n"
+		"	.set	arch=r4000				\n"
 		"2:	sc	$1, %2					\n"
 		"	beqzl	$1, 1b					\n"
 		__WEAK_LLSC_MB
@@ -174,12 +174,12 @@
 		"# futex_atomic_cmpxchg_inatomic			\n"
 		"	.set	push					\n"
 		"	.set	noat					\n"
-		"	.set	mips3					\n"
+		"	.set	arch=r4000				\n"
 		"1:	"user_ll("%1", "%3")"				\n"
 		"	bne	%1, %z4, 3f				\n"
 		"	.set	mips0					\n"
 		"	move	$1, %z5					\n"
-		"	.set	mips3					\n"
+		"	.set	arch=r4000				\n"
 		"2:	"user_sc("$1", "%2")"				\n"
 		"	beqz	$1, 1b					\n"
 		__WEAK_LLSC_MB