x86: SGI UV: Map low MMR ranges

Explicitly mmap the UV chipset MMR address ranges used to
access blade-local registers. Although these same MMRs are also
mmaped at higher addresses, the low range is more
convenient when accessing blade-local registers.

The low range addresses always alias to the local blade
regardless of the blade id.

Signed-off-by: Jack Steiner <steiner@sgi.com>
LKML-Reference: <20091125162018.GA25445@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>