h8300: Limit timer channel ranges in Kconfig

arch/h8300/kernel/timer/itu.c and arch/h8300/kernel/timer/tpu.c
only support 0--4 for CONFIG_H8300_ITU_CH resp. H8300_TPU_CH, hence limit
them to that range in Kconfig.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

arch/h8300/Kconfig.cpu

@@ -155,10 +155,12 @@ config H8300_TIMER16_CH
 config H8300_ITU_CH
 	int "ITU channel"
 	depends on H8300_ITU
+	range 0 4
 
 config H8300_TPU_CH
 	int "TPU channel"
 	depends on H8300_TPU
+	range 0 4
 
 source "kernel/Kconfig.preempt"