boards: up_squared_adsp: provide default memctl in linker script
boards: up_squared_adsp: provide default memctl in linker script

Both memctl_default.S and memerror-vector.S (inside
arch/xtensa/core/startup) refer to XCHAL_CACHE_MEMCTL_DEFAULT which
is not defined anywhere. The linker script for intel_apl_adsp SoC
provides default values, but not the bootloader linker script. So
provide the same default value in the bootloader linker script as
in the SoC linker script.

Signed-off-by: Daniel Leung <d94e04d205b5962d7873a139ef298b03c1717f72@intel.com>

nashif/zephyr,nashif/zephyr,nashif/zephyr,galak/zephyr,finikorg/zephyr,finikorg/zephyr,finikorg/zephyr,nashif/zephyr,nashif/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,Vudentz/zephyr,zephyrproject-rtos/zephyr,Vudentz/zephyr,finikorg/zephyr,galak/zephyr,Vudentz/zephyr,Vudentz/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr