sh: smp: Fix missing prototypes

sh: smp: Fix missing prototypes

arch/sh/kernel/smp.c:173:17: warning: no previous prototype for 'start_secondary' [-Wmissing-prototypes]
arch/sh/kernel/smp.c:324:5: warning: no previous prototype for 'setup_profiling_timer' [-Wmissing-prototypes]

Make start_secondary() static, as it is only used in this file.
Include <linux/profile.h> to fix the other warning.

There are no users outside this file, so make it static.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Link: https://lore.kernel.org/r/6b6b9a84b30ee56f57f409a7550c69d4aece5dc3.1709326528.git.geert+renesas@glider.be
Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>