[MIPS] Fix FIXADDR_TOP for TX39/TX49.

FIXADDR_TOP is used for HIGHMEM and for upper limit of vmalloc area on
32bit kernel.  TX39XX and TX49XX have "reserved" segment in CKSEG3
area.  0xff000000-0xff3fffff on TX49XX and 0xff000000-0xfffeffff on
TX39XX are reserved (unmapped, uncached) therefore can not be used as
mapped area.
Signed-off-by: NAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

include/asm-mips/fixmap.h

@@ -69,7 +69,11 @@ extern void __set_fixmap (enum fixed_addresses idx,
  * the start of the fixmap, and leave one page empty
  * at the top of mem..
  */
+#if defined(CONFIG_CPU_TX39XX) || defined(CONFIG_CPU_TX49XX)
+#define FIXADDR_TOP	(0xff000000UL - 0x2000)
+#else
 #define FIXADDR_TOP	(0xffffe000UL)
+#endif
 #define FIXADDR_SIZE	(__end_of_fixed_addresses << PAGE_SHIFT)
 #define FIXADDR_START	(FIXADDR_TOP - FIXADDR_SIZE)