ARM: OMAP2+: change the ISP device archdata MMU name for DT

ARM: OMAP2+: change the ISP device archdata MMU name for DT

The IOMMU DT adaptation support uses the device name instead
of an iommu object name. Fixup the ISP device archdata MMU
name at runtime if using DT-boot. This allows the OMAP3 camera
to be functional in both legacy and DT boots. The iommu object
names should eventually vanish when all the IOMMU users have
been converted to DT nodes.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>