nfsd: NFSD_FAULT_INJECTION depends on DEBUG_FS

NFSD_FAULT_INJECTION depends on DEBUG_FS, otherwise the debugfs_create_*
interface may return unexpected error -ENODEV, and cause system crash.
Signed-off-by: Chengyu Song <csong84@gatech.edu>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/Kconfig

@@ -107,7 +107,7 @@ config NFSD_V4_SECURITY_LABEL
 
 config NFSD_FAULT_INJECTION
 	bool "NFS server manual fault injection"
-	depends on NFSD_V4 && DEBUG_KERNEL
+	depends on NFSD_V4 && DEBUG_KERNEL && DEBUG_FS
 	help
 	  This option enables support for manually injecting faults
 	  into the NFS server.  This is intended to be used for