fix vmpath when invoked with a path to config file

src/pc.c

@@ -440,9 +440,6 @@ usage:
 		plat_dir_create(usr_path);
     }
 
-    /* Make sure we have a trailing backslash. */
-    plat_path_slash(usr_path);
-
     /* Grab the name of the configuration file. */
     if (cfg == NULL)
 	cfg = CONFIG_FILE;
@@ -476,6 +473,9 @@ usage:
 		wcscat(usr_path, cfg);
     }
 
+    /* Make sure we have a trailing backslash. */
+    plat_path_slash(usr_path);
+
     /* At this point, we can safely create the full path name. */
     plat_append_filename(cfg_path, usr_path, p);