xtensa: smp: add headers for missing function prototypes

Use <asm/smp.h> to provide the prototype for secondary_start_kernel().
Use <linux/profile.h> to provide the prototype for
setup_profiling_timer().

arch/xtensa/kernel/smp.c:119:6: warning: no previous prototype for 'secondary_start_kernel' [-Wmissing-prototypes]
  119 | void secondary_start_kernel(void)
arch/xtensa/kernel/smp.c:461:5: warning: no previous prototype for 'setup_profiling_timer' [-Wmissing-prototypes]
  461 | int setup_profiling_timer(unsigned int multiplier)
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Message-Id: <20230920052139.10570-11-rdunlap@infradead.org>
Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>

arch/xtensa/include/asm/smp.h

@@ -23,6 +23,7 @@ struct cpumask;
 void arch_send_call_function_ipi_mask(const struct cpumask *mask);
 void arch_send_call_function_single_ipi(int cpu);
 
+void secondary_start_kernel(void);
 void smp_init_cpus(void);
 void secondary_init_irq(void);
 void ipi_init(void);

arch/xtensa/kernel/smp.c

@@ -21,6 +21,7 @@
 #include <linux/irq.h>
 #include <linux/kdebug.h>
 #include <linux/module.h>
+#include <linux/profile.h>
 #include <linux/sched/mm.h>
 #include <linux/sched/hotplug.h>
 #include <linux/sched/task_stack.h>