Provide debugfs function stubs when EDAC_DEBUG is not enabled so that we
don't fail the build:
drivers/edac/pnd2_edac.c: In function ‘pnd2_init’:
drivers/edac/pnd2_edac.c:1521:2: error: implicit declaration of function ‘setup_pnd2_debug’ [-Werror=implicit-function-declaration]
setup_pnd2_debug();
^
drivers/edac/pnd2_edac.c: In function ‘pnd2_exit’:
drivers/edac/pnd2_edac.c:1529:2: error: implicit declaration of function ‘teardown_pnd2_debug’ [-Werror=implicit-function-declaration]
teardown_pnd2_debug();
^