ARM: 8432/1: move VMALLOC_END from 0xff000000 to 0xff800000

There is a 12MB unused region in our memory map between the vmalloc and
fixmap areas. This became unused with commit e9da6e9, confirmed
with commit 64d3b6a.

We also have a 8MB guard area before the vmalloc area.  With the default
240MB vmalloc area size and the current VMALLOC_END definition, that
means the end of low memory ends up at 0xef800000 which is unfortunate
for 768MB machines where 8MB of RAM is lost to himem.

Let's move VMALLOC_END to 0xff800000 so the guard area won't chop the
top of the 768MB low memory area while keeping the default vmalloc area
size unchanged and still preserving a gap between the vmalloc and fixmap
areas.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

Documentation/arm/memory.txt

@@ -54,7 +54,7 @@ VMALLOC_START	VMALLOC_END-1	vmalloc() / ioremap() space.
 				located here through iotable_init().
 				VMALLOC_START is based upon the value
 				of the high_memory variable, and VMALLOC_END
-				is equal to 0xff000000.
+				is equal to 0xff800000.
 
 PAGE_OFFSET	high_memory-1	Kernel direct-mapped RAM region.
 				This maps the platforms RAM, and typically

arch/arm/include/asm/pgtable.h

@@ -43,7 +43,7 @@
  */
 #define VMALLOC_OFFSET		(8*1024*1024)
 #define VMALLOC_START		(((unsigned long)high_memory + VMALLOC_OFFSET) & ~(VMALLOC_OFFSET-1))
-#define VMALLOC_END		0xff000000UL
+#define VMALLOC_END		0xff800000UL
 
 #define LIBRARY_TEXT_START	0x0c000000