MIPS: fpu.h: Fix build when CONFIG_BUG is not set

__enable_fpu produces a build failure when CONFIG_BUG is not set:

In file included from arch/mips/kernel/cpu-probe.c:24:0:
arch/mips/include/asm/fpu.h: In function '__enable_fpu':
arch/mips/include/asm/fpu.h:77:1: error: control reaches end of non-void function [-Werror=return-type]

This is regression introduced in 3.14-rc1. Fix that.
Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
Acked-by: Paul Burton <paul.burton@imgtec.com>
Cc: John Crispin <blogic@openwrt.org>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/6504/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/fpu.h

@@ -74,6 +74,8 @@ static inline int __enable_fpu(enum fpu_mode mode)
 	default:
 		BUG();
 	}
+
+	return SIGFPE;
 }
 
 #define __disable_fpu()							\