ARM: OMAP2+: Trivial fix for IOMMU merge issue

Commit 787314c3 ("Merge tag 'iommu-updates-v3.8' of
git://git./linux/kernel/git/joro/iommu"

) did not account for the changed
header location.

The headers were made local to mach-omap2 as they are specific to omap2+
only, and we wanted to get most of the #include <plat/*.h> headers fixed
up anyways for the ARM multiplatform support.

We attempted to avoid this kind of merge conflict early on by setting up
a minimal git branch shared by the arm-soc tree and the iommu tree, but
looks like we still hit a merge issue there as the branches got merged
as various topic branches.

Cc: Joerg Roedel <joro@8bytes.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>