m68k: hp300: Include "time.h" for hp300_sched_init()

When building with W=1:

    arch/m68k/hp300/time.c:101:13: warning: no previous prototype for ‘hp300_sched_init’ [-Wmissing-prototypes]
      101 | void __init hp300_sched_init(void)
	  |             ^~~~~~~~~~~~~~~~

Fix this by including "time.h".

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/630ee35241dc753a30b69adedc2ffa8fc6d551dd.1694613528.git.geert@linux-m68k.org