fs: Move conditional compilation to Makefile

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
diff --git a/fs/fdos/fdos.c b/fs/fdos/fdos.c
index 5be6a96..db58562 100644
--- a/fs/fdos/fdos.c
+++ b/fs/fdos/fdos.c
@@ -24,9 +24,8 @@
 
 #include <common.h>
 #include <config.h>
-
-#if defined(CONFIG_CMD_FDOS)
 #include <malloc.h>
+
 #include "dos.h"
 #include "fdos.h"
 
@@ -171,5 +170,3 @@
     free (name);
     return (0);
 }
-
-#endif