OMAP2420 IO mapping: move IVA mapping virtual address out of vmalloc space

Commit 10db25fe causes the following
kernel messages during N800 boot (and presumably all other 2420
boards):

[    0.000000] BUG: mapping for 0x58000000 at 0xe0000000 overlaps vmalloc space
[    0.000000] BUG: mapping for 0x59000000 at 0xe1000000 overlaps vmalloc space
[    0.000000] BUG: mapping for 0x5a000000 at 0xe2000000 overlaps vmalloc space

Fix by remapping the IVA memory areas somewhere outside vmalloc space.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Tony Lindgren <tony@atomide.com>