omap: iommu: program constraints based on platform data

IOMMU driver requests and releases constraints in iommu_get
and iommu_put respectively. These constraints are actually
needed only on OMAP4 and beyond for sub-systems that have
an AMMU. The current driver code has these values hard-coded
for all the chips.

A new platform data field has been added now for the constraints
values, and this allows the values to be programmed based on
the OMAP chip and also allow a unique value if needed for each
iommu instance.

The logic in IOMMU driver code is adjusted to request the
constraints only if the relevant platform data field is set.

Change-Id: Iab18cbdde1d7fa7507dbff0b9512c8577b42fefd
Signed-off-by: Subramaniam C.A <subramaniam.ca@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>

Conflicts:
	arch/arm/mach-omap2/omap-iommu.c