sh: kprobes: Make trampoline_probe_handler() static

sh: kprobes: Make trampoline_probe_handler() static

arch/sh/kernel/kprobes.c:299:15: warning: no previous prototype for 'trampoline_probe_handler' [-Wmissing-prototypes]

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/42f30b7f767ee1293f6e687a605f7d907ae2daa6.1709326528.git.geert+renesas@glider.be
Signed-off-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>