MIPS: MSP71xx: Remove compilation error when CONFIG_MIPS_MT is present

When CONFIG_MIPS_MT is defined, code is enabled that tries to call
'set_vi_handler()'. This function is declared in <asm/setup.h> but the
header is never included. Therefore, the compilation breaks.

arch/mips/pmcs-msp71xx/msp_irq.c:133: error: implicit declaration of function 'set_vi_handler'

This error was found with vampyr.
Signed-off-by: Stefan Hengelein <stefan.hengelein@fau.de>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Cc: ryazanov.s.a@gmail.com
Patchwork: https://patchwork.linux-mips.org/patch/8122/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/pmcs-msp71xx/msp_irq.c

@@ -16,6 +16,7 @@
 #include <linux/time.h>
 
 #include <asm/irq_cpu.h>
+#include <asm/setup.h>
 
 #include <msp_int.h>