picoxcell: add a definition of VMALLOC_END

Nicolas Pitre's vmalloc cleanup series didn't get merged in this cycle
so picoxcell is missing a VMALLOC_END definition.
Signed-off-by: Jamie Iles <jamie@jamieiles.com>

arch/arm/mach-picoxcell/include/mach/vmalloc.h

+/*
+ * Copyright (c) 2011 Picochip Ltd., Jamie Iles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+#define VMALLOC_END	0xfe000000UL