The generic IOMMU binding says that the meaning of an 'IOMMU specifier'
is defined by the binding of a specific SMMU.  The ARM SMMU binding
never explicitly uses the term 'specifier' at all.  Update implicit
references to use the explicit term.

In the iommu-map binding change references to iommu-specifier to
"IOMMU specifier" so we are 100% consistent everywhere with terminology
and capitalization.
Signed-off-by: NStuart Yoder <stuart.yoder@nxp.com>
Acked-by: NMark Rutland <mark.rutland@arm.com>
Signed-off-by: NRob Herring <robh@kernel.org>