[PATCH] x86: enable VMSPLIT for highmem kernels

The current VMSPLIT Kconfig option is disabled whenever highmem is on.
This is a bit screwy because the people who need to change VMSPLIT the most
tend to be the ones with highmem and constrained lowmem.

So, remove the highmem dependency.  But, re-include the dependency for the
"full 1GB of lowmem" option.  You can't have the full 1GB of lowmem and
highmem because of the need for the vmalloc(), kmap(), etc...  areas.

I thought there would be at least a bit of tweaking to do to
get it to work, but everything seems OK.

Boot tested on a 4GB x86 machine, and a 12GB 3-node NUMA-Q:

elm3b82:~# cat /proc/meminfo
MemTotal:      3695412 kB
MemFree:       3659540 kB
...
LowTotal:      2909008 kB
LowFree:       2892324 kB
...
elm3b82:~# zgrep PAE /proc/config.gz
CONFIG_X86_PAE=y

larry:~# cat /proc/meminfo
MemTotal:     11845900 kB
MemFree:      11786748 kB
...
LowTotal:      2855180 kB
LowFree:       2830092 kB

Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>