[MIPS] Rewrite spurious_interrupt from assembler to C.

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

arch/mips/dec/int-handler.S

@@ -282,7 +282,9 @@ fpu:
 #endif
 
 spurious:
-		j	spurious_interrupt
+		jal	spurious_interrupt
+		 nop
+		j	ret_from_irq
 		 nop
 		END(decstation_handle_int)