kernel: mem_domain: remove extra slash in Z_PROGBITS_SYM
kernel: mem_domain: remove extra slash in Z_PROGBITS_SYM

The macro Z_PROGBITS_SYM has "\%" but this is not correct
usage to escape "%". So remove the extra slash. Note that
this macro is used directly to generate assembly code
so it cannot be "%%" as in escaping "%" in printf().

Fixes #40439

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

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