x86: SGI UV: Map MMIO-High memory range

UV depends on the MMRHI space being identity mapped. The patch:

	x86: Make 64-bit efi_ioremap use ioremap on MMIO regions

changed this to make efi regions at a different address using
ioremap. Add the identity mapping to uv_system_init.

( Note this code was previously present but was deleted when BIOS
  added the ranges to the EFI map - previous efi code identify
  mapped the ranges. )

Signed-off-by: Jack Steiner <steiner@sgi.com>
LKML-Reference: <20090909154339.GA7946@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>