[linux-next:master 11510/13217] cxl.c:undefined reference to `to_cxl_dax_region'

[linux-next:master 11510/13217] cxl.c:undefined reference to `to_cxl_dax_region'

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   509583475828c4fd86897113f78315c1431edcc3
commit: 09d09e04d2fcf88c4620dd28097e0e2a8f720eac [11510/13217] cxl/dax: Create dax devices for CXL RAM regions
config: s390-randconfig-r005-20230212 (https://download.01.org/0day-ci/archive/20230216/202302162331.zGyXCiuH-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=09d09e04d2fcf88c4620dd28097e0e2a8f720eac
        git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
        git fetch --no-tags linux-next master
        git checkout 09d09e04d2fcf88c4620dd28097e0e2a8f720eac
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=s390 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202302162331.zGyXCiuH-lkp@intel.com/

All errors (new ones prefixed by >>):

   s390-linux-ld: drivers/dax/cxl.o: in function `cxl_dax_region_probe':
>> cxl.c:(.text+0x92): undefined reference to `to_cxl_dax_region'
   s390-linux-ld: drivers/dax/cxl.o: in function `cxl_dax_region_driver_init':
>> cxl.c:(.init.text+0x3c): undefined reference to `__cxl_driver_register'
   s390-linux-ld: drivers/dax/cxl.o: in function `cxl_dax_region_driver_exit':
>> cxl.c:(.exit.text+0x32): undefined reference to `cxl_driver_unregister'

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests