fault-inject: fix build error when FAULT_INJECTION_CONFIGFS=y and CONFIGFS_FS=m

This fixes a build error when CONFIG_FAULT_INJECTION_CONFIGFS=y and
CONFIG_CONFIGFS_FS=m.

Since the fault-injection library cannot built as a module, avoid building
configfs as a module.

Fixes: 4668c7a ("fault-inject: allow configuration via configfs")
Reported-by: kernel test robot <[email protected]>
Link: https://lore.kernel.org/oe-kbuild-all/[email protected]/
Signed-off-by: Akinobu Mita <[email protected]>
Signed-off-by: Jens Axboe <[email protected]>

Author: mita

lib/Kconfig.debug

@@ -1960,7 +1960,8 @@ config FAIL_SUNRPC
 
 config FAULT_INJECTION_CONFIGFS
 	bool "Configfs interface for fault-injection capabilities"
-	depends on FAULT_INJECTION && CONFIGFS_FS
+	depends on FAULT_INJECTION
+	select CONFIGFS_FS
 	help
 	  This option allows configfs-based drivers to dynamically configure
 	  fault-injection via configfs.  Each parameter for driver-specific