fs: Make unload_nls() NULL pointer safe

Most call sites of unload_nls() do:
	if (nls)
		unload_nls(nls);

Check the pointer inside unload_nls() like we do in kfree() and
simplify the call sites.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steve French <sfrench@us.ibm.com>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Petr Vandrovec <vandrove@vc.cvut.cz>
Cc: Anton Altaparmakov <aia21@cantab.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ncpfs/inode.c b/fs/ncpfs/inode.c
index b99ce20..cf98da1 100644
--- a/fs/ncpfs/inode.c
+++ b/fs/ncpfs/inode.c
@@ -746,16 +746,8 @@
 
 #ifdef CONFIG_NCPFS_NLS
 	/* unload the NLS charsets */
-	if (server->nls_vol)
-	{
-		unload_nls(server->nls_vol);
-		server->nls_vol = NULL;
-	}
-	if (server->nls_io)
-	{
-		unload_nls(server->nls_io);
-		server->nls_io = NULL;
-	}
+	unload_nls(server->nls_vol);
+	unload_nls(server->nls_io);
 #endif /* CONFIG_NCPFS_NLS */
 
 	if (server->info_filp)