MIPS: process: Fix no previous prototype warning

unwind_stack_by_address and unwind_stack need <asm/stacktrace.h>.
arch_align_stack needs <asm/exec.h>

link: https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/ZPL2RRA6RZKRQZI5IGOVLFXN2GVZBN3L/Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jinyang He <hejinyang@loongson.cn>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/kernel/process.c

@@ -26,6 +26,7 @@
 #include <asm/asm.h>
 #include <asm/dsemul.h>
 #include <asm/dsp.h>
+#include <asm/exec.h>
 #include <asm/fpu.h>
 #include <asm/inst.h>
 #include <asm/irq.h>
@@ -36,6 +37,7 @@
 #include <asm/mipsregs.h>
 #include <asm/processor.h>
 #include <asm/reg.h>
+#include <asm/stacktrace.h>
 
 #ifdef CONFIG_HOTPLUG_CPU
 void arch_cpu_idle_dead(void)