ite/it8xxx2: avoid cpu entering deep doze mode when JTAG is enabled

Prevent the CPU from entering deep doze mode when JTAG debug is enabled.
Additionally, The CPU address from 0x80000800 to 0x800008FF should be
reserved for JTAG debug usage. This commit reserves the area from the end
of the reset section to 0x800008FF if JTAG debug is enabled.

Tested with:
- west build -p always -b it82xx2_evb samples/hello_world/
       -DCONFIG_SOC_IT8XXX2_JTAG_DEBUG_INTERFACE=y

Signed-off-by: Ren Chen <Ren.Chen@ite.com.tw>