MIPS: Override assembler target architecture for octeon.

Gas from binutils 2.19 fails to compile some cop1 instructions with
-march=octeon.  Since the cop1 instructions are present in mips1, use
that arch instead.  This will be fixed in binutils 2.20.

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/mipsregs.h

@@ -1028,6 +1028,8 @@ do {									\
 	__asm__ __volatile__(                                   \
 	".set\tpush\n\t"					\
 	".set\treorder\n\t"					\
+	/* gas fails to assemble cfc1 for some archs (octeon).*/ \
+	".set\tmips1\n\t"					\
         "cfc1\t%0,"STR(source)"\n\t"                            \
 	".set\tpop"						\
         : "=r" (__res));                                        \